Solutions

Cargo.lock

@@ -205,6 +205,7 @@ dependencies = [
 name = "bounded"
 version = "0.1.0"
 dependencies = [
+ "thiserror",
  "ticket_fields",
 ]
 
@@ -443,6 +444,9 @@ dependencies = [
 [[package]]
 name = "deps"
 version = "0.1.0"
+dependencies = [
+ "anyhow",
+]
 
 [[package]]
 name = "deref"
@@ -1439,6 +1443,9 @@ version = "0.1.0"
 [[package]]
 name = "outro_04"
 version = "0.1.0"
+dependencies = [
+ "thiserror",
+]
 
 [[package]]
 name = "outro_08"
@@ -2175,6 +2182,7 @@ name = "thiserror_"
 version = "0.1.0"
 dependencies = [
  "common",
+ "thiserror",
 ]
 
 [[package]]
@@ -2316,6 +2324,9 @@ checksum = "e421abadd41a4225275504ea4d6566923418b7f05506fbc9c0fe86ba7396114b"
 [[package]]
 name = "tryfrom"
 version = "0.1.0"
+dependencies = [
+ "thiserror",
+]
 
 [[package]]
 name = "tungstenite"

Cargo.toml

@@ -12,3 +12,6 @@ resolver = "2"
 # regardless of the "global" setting for `overflow-checks` on the `dev` profile.
 [profile.dev.package.copy]
 overflow-checks = true
+
+[profile.dev]
+overflow-checks = false

exercises/01_intro/00_welcome/src/lib.rs

@@ -17,7 +17,7 @@
 // You can also find solutions to all exercises in the `solutions` git branch.
 fn greeting() -> &'static str {
     // TODO: fix me 👇
-    "I'm ready to __!"
+    "I'm ready to learn Rust!"
 }
 
 // Your solutions will be automatically verified by a set of tests.

exercises/01_intro/01_syntax/src/lib.rs

@@ -3,7 +3,7 @@
 //  partner in this course and it'll often guide you in the right direction!
 //
 // The input parameters should have the same type of the return type.
-fn compute(a, b) -> u32 {
+fn compute(a: u32, b: u32) -> u32 {
     // Don't touch the function body.
     a + b * 2
 }
@@ -16,4 +16,4 @@ mod tests {
     fn case() {
         assert_eq!(compute(1, 2), 5);
     }
-}
+}

exercises/02_basic_calculator/00_intro/src/lib.rs

@@ -1,6 +1,6 @@
 fn intro() -> &'static str {
     // TODO: fix me 👇
-    "I'm ready to __!"
+    "I'm ready to build a calculator in Rust!"
 }
 
 #[cfg(test)]

exercises/02_basic_calculator/01_integers/src/lib.rs

@@ -1,6 +1,7 @@
 fn compute(a: u32, b: u32) -> u32 {
-    // TODO: change the line below to fix the compiler error and make the tests pass.
+    let multiplier: u32 = 4;
-    let multiplier: u8 = 4;
+    // ^ You could also omit `: u32` entirely.
+    // The compiler will infer the correct type based on the usage below.
     a + b * multiplier
 }
 

exercises/02_basic_calculator/02_variables/src/lib.rs

@@ -8,6 +8,7 @@
 pub fn speed(start: u32, end: u32, time_elapsed: u32) -> u32 {
     // TODO: define a variable named `distance` with the right value to get tests to pass
     //  Do you need to annotate the type of `distance`? Why or why not?
+    let distance = end - start;
 
     // Don't change the line below
     distance / time_elapsed

exercises/02_basic_calculator/03_if_else/src/lib.rs

@@ -2,7 +2,13 @@
 /// `13` if `n` is divisible by `3`,
 /// `17` otherwise.
 fn magic_number(n: u32) -> u32 {
-    todo!()
+    if n % 2 == 0 {
+        12
+    } else if n % 3 == 0 {
+        13
+    } else {
+        17
+    }
 }
 
 #[cfg(test)]

exercises/02_basic_calculator/04_panics/src/lib.rs

@@ -2,6 +2,9 @@
 /// calculate the average speed of the journey.
 fn speed(start: u32, end: u32, time_elapsed: u32) -> u32 {
     // TODO: Panic with a custom message if `time_elapsed` is 0
+    if time_elapsed == 0 {
+        panic!("The journey took no time at all, that's impossible!");
+    }
 
     (end - start) / time_elapsed
 }

exercises/02_basic_calculator/05_factorial/src/lib.rs

@@ -9,6 +9,13 @@
 // `factorial(2)` to return `2`, and so on.
 //
 // Use only what you learned! No loops yet, so you'll have to use recursion!
+fn factorial(n: u32) -> u32 {
+    if n == 0 {
+        1
+    } else {
+        n * factorial(n - 1)
+    }
+}
 
 #[cfg(test)]
 mod tests {

exercises/02_basic_calculator/06_while/src/lib.rs

@@ -4,7 +4,13 @@ pub fn factorial(n: u32) -> u32 {
     // interprets as "I'll get back to this later", thus
     // suppressing type errors.
     // It panics at runtime.
-    todo!()
+    let mut result = 1;
+    let mut i = 1;
+    while i <= n {
+        result *= i;
+        i += 1;
+    }
+    result
 }
 
 #[cfg(test)]

exercises/02_basic_calculator/07_for/src/lib.rs

@@ -1,6 +1,10 @@
 // Rewrite the factorial function using a `for` loop.
 pub fn factorial(n: u32) -> u32 {
-    todo!()
+    let mut result = 1;
+    for i in 1..=n {
+        result *= i;
+    }
+    result
 }
 
 #[cfg(test)]

exercises/02_basic_calculator/09_saturating/src/lib.rs

@@ -1,9 +1,9 @@
 pub fn factorial(n: u32) -> u32 {
-    let mut result = 1;
+    let mut result: u32 = 1;
     for i in 1..=n {
         // Use saturating multiplication to stop at the maximum value of u32
         // rather than overflowing and wrapping around
-        result *= i;
+        result = result.saturating_mul(i);
     }
     result
 }

exercises/02_basic_calculator/10_as_casting/src/lib.rs

@@ -6,7 +6,7 @@ mod tests {
 
     #[test]
     fn u16_to_u32() {
-        let v: u32 = todo!();
+        let v: u32 = 47;
         assert_eq!(47u16 as u32, v);
     }
 
@@ -23,15 +23,15 @@ mod tests {
 
         // You could solve this by using exactly the same expression as above,
         // but that would defeat the purpose of the exercise. Instead, use a genuine
-        // `i8` value that is equivalent to `255` when converted to `u8`.
+        // `i8` value that is equivalent to `255` when converted from `u8`.
-        let y: i8 = todo!();
+        let y: i8 = -1;
 
         assert_eq!(x, y);
     }
 
     #[test]
     fn bool_to_u8() {
-        let v: u8 = todo!();
+        let v: u8 = 1;
         assert_eq!(true as u8, v);
     }
 }

exercises/03_ticket_v1/00_intro/src/lib.rs

@@ -1,6 +1,6 @@
 fn intro() -> &'static str {
     // TODO: fix me 👇
-    "I'm ready to __!"
+    "I'm ready to start modelling a software ticket!"
 }
 
 #[cfg(test)]

exercises/03_ticket_v1/01_struct/src/lib.rs

@@ -4,6 +4,16 @@
 //
 // It should also have a method named `is_available` that returns a `true` if the quantity is
 // greater than 0, otherwise `false`.
+struct Order {
+    price: u32,
+    quantity: u32,
+}
+
+impl Order {
+    fn is_available(&self) -> bool {
+        self.quantity > 0
+    }
+}
 
 #[cfg(test)]
 mod tests {

exercises/03_ticket_v1/02_validation/src/lib.rs

@@ -18,7 +18,24 @@ impl Ticket {
     // as well as some `String` methods. Use the documentation of Rust's standard library
     // to find the most appropriate options -> https://doc.rust-lang.org/std/string/struct.String.html
     fn new(title: String, description: String, status: String) -> Self {
-        todo!();
+        if title.is_empty() {
+            panic!("Title cannot be empty");
+        }
+        if title.len() > 50 {
+            panic!("Title cannot be longer than 50 bytes");
+        }
+
+        if description.is_empty() {
+            panic!("Description cannot be empty");
+        }
+        if description.len() > 500 {
+            panic!("Description cannot be longer than 500 bytes");
+        }
+
+        if status != "To-Do" && status != "In Progress" && status != "Done" {
+            panic!("Only `To-Do`, `In Progress`, and `Done` statuses are allowed");
+        }
+
         Self {
             title,
             description,

exercises/03_ticket_v1/03_modules/src/lib.rs

@@ -1,6 +1,7 @@
 mod helpers {
     // TODO: Make this code compile, either by adding a `use` statement or by using
     //  the appropriate path to refer to the `Ticket` struct.
+    use super::Ticket;
 
     fn create_todo_ticket(title: String, description: String) -> Ticket {
         Ticket::new(title, description, "To-Do".into())

exercises/03_ticket_v1/04_visibility/src/lib.rs

@@ -1,12 +1,12 @@
 mod ticket {
-    struct Ticket {
+    pub struct Ticket {
         title: String,
         description: String,
         status: String,
     }
 
     impl Ticket {
-        fn new(title: String, description: String, status: String) -> Ticket {
+        pub fn new(title: String, description: String, status: String) -> Ticket {
             if title.is_empty() {
                 panic!("Title cannot be empty");
             }
@@ -55,7 +55,7 @@ mod tests {
         //
         // TODO: Once you have verified that the below does not compile,
         //   comment the line out to move on to the next exercise!
-        assert_eq!(ticket.description, "A description");
+        // assert_eq!(ticket.description, "A description");
     }
 
     fn encapsulation_cannot_be_violated() {
@@ -68,10 +68,10 @@ mod tests {
         //
         // TODO: Once you have verified that the below does not compile,
         //   comment the lines out to move on to the next exercise!
-        let ticket = Ticket {
+        // let ticket = Ticket {
-            title: "A title".into(),
+        //     title: "A title".into(),
-            description: "A description".into(),
+        //     description: "A description".into(),
-            status: "To-Do".into(),
+        //     status: "To-Do".into(),
-        };
+        // };
     }
 }

exercises/03_ticket_v1/05_encapsulation/src/lib.rs

@@ -34,6 +34,17 @@ pub mod ticket {
         //  - `title` that returns the `title` field.
         //  - `description` that returns the `description` field.
         //  - `status` that returns the `status` field.
+        pub fn title(self) -> String {
+            self.title
+        }
+
+        pub fn description(self) -> String {
+            self.description
+        }
+
+        pub fn status(self) -> String {
+            self.status
+        }
     }
 }
 

exercises/03_ticket_v1/06_ownership/src/lib.rs

@@ -34,16 +34,16 @@ impl Ticket {
         }
     }
 
-    pub fn title(self) -> String {
+    pub fn title(&self) -> &String {
-        self.title
+        &self.title
     }
 
-    pub fn description(self) -> String {
+    pub fn description(&self) -> &String {
-        self.description
+        &self.description
     }
 
-    pub fn status(self) -> String {
+    pub fn status(&self) -> &String {
-        self.status
+        &self.status
     }
 }
 

exercises/03_ticket_v1/07_setters/src/lib.rs

@@ -11,21 +11,9 @@ pub struct Ticket {
 
 impl Ticket {
     pub fn new(title: String, description: String, status: String) -> Ticket {
-        if title.is_empty() {
+        validate_title(&title);
-            panic!("Title cannot be empty");
+        validate_description(&description);
-        }
+        validate_status(&status);
-        if title.len() > 50 {
-            panic!("Title cannot be longer than 50 bytes");
-        }
-        if description.is_empty() {
-            panic!("Description cannot be empty");
-        }
-        if description.len() > 500 {
-            panic!("Description cannot be longer than 500 bytes");
-        }
-        if status != "To-Do" && status != "In Progress" && status != "Done" {
-            panic!("Only `To-Do`, `In Progress`, and `Done` statuses are allowed");
-        }
 
         Ticket {
             title,
@@ -45,6 +33,45 @@ impl Ticket {
     pub fn status(&self) -> &String {
         &self.status
     }
+
+    pub fn set_title(&mut self, title: String) {
+        validate_title(&title);
+        self.title = title;
+    }
+
+    pub fn set_description(&mut self, description: String) {
+        validate_description(&description);
+        self.description = description;
+    }
+
+    pub fn set_status(&mut self, status: String) {
+        validate_status(&status);
+        self.status = status;
+    }
+}
+
+fn validate_title(title: &String) {
+    if title.is_empty() {
+        panic!("Title cannot be empty");
+    }
+    if title.len() > 50 {
+        panic!("Title cannot be longer than 50 bytes");
+    }
+}
+
+fn validate_description(description: &String) {
+    if description.is_empty() {
+        panic!("Description cannot be empty");
+    }
+    if description.len() > 500 {
+        panic!("Description cannot be longer than 500 bytes");
+    }
+}
+
+fn validate_status(status: &String) {
+    if status != "To-Do" && status != "In Progress" && status != "Done" {
+        panic!("Only `To-Do`, `In Progress`, and `Done` statuses are allowed");
+    }
 }
 
 #[cfg(test)]

exercises/03_ticket_v1/08_stack/src/lib.rs

@@ -6,16 +6,16 @@ mod tests {
 
     #[test]
     fn u16_size() {
-        assert_eq!(size_of::<u16>(), todo!());
+        assert_eq!(size_of::<u16>(), 2);
     }
 
     #[test]
     fn i32_size() {
-        assert_eq!(size_of::<i32>(), todo!());
+        assert_eq!(size_of::<i32>(), 4);
     }
 
     #[test]
     fn bool_size() {
-        assert_eq!(size_of::<bool>(), todo!());
+        assert_eq!(size_of::<bool>(), 1);
     }
 }

exercises/03_ticket_v1/09_heap/src/lib.rs

@@ -13,7 +13,7 @@ mod tests {
 
     #[test]
     fn string_size() {
-        assert_eq!(size_of::<String>(), todo!());
+        assert_eq!(size_of::<String>(), 24);
     }
 
     #[test]
@@ -21,8 +21,8 @@ mod tests {
         // This is a tricky question!
         // The "intuitive" answer happens to be the correct answer this time,
         // but, in general, the memory layout of structs is a more complex topic.
-        // If you're curious, check out the "Type layout" section of The Rust Reference
+        // If you're curious, check out the "Data layout" section of the Rustonomicon
-        // https://doc.rust-lang.org/reference/type-layout.html for more information.
+        // https://doc.rust-lang.org/nomicon/data.html for more information.
-        assert_eq!(size_of::<Ticket>(), todo!());
+        assert_eq!(size_of::<Ticket>(), 72);
     }
 }

exercises/03_ticket_v1/10_references_in_memory/src/lib.rs

@@ -11,18 +11,21 @@ mod tests {
     use super::Ticket;
     use std::mem::size_of;
 
+    // All numbers below assume you're running on a 64-bit system.
+    // If you're running on a 32-bit system, pointers will be 4 bytes long instead of 8.
+
     #[test]
     fn u16_ref_size() {
-        assert_eq!(size_of::<&u16>(), todo!());
+        assert_eq!(size_of::<&u16>(), 8);
     }
 
     #[test]
     fn u64_mut_ref_size() {
-        assert_eq!(size_of::<&mut u64>(), todo!());
+        assert_eq!(size_of::<&mut u64>(), 8);
     }
 
     #[test]
     fn ticket_ref_size() {
-        assert_eq!(size_of::<&Ticket>(), todo!());
+        assert_eq!(size_of::<&Ticket>(), 8);
     }
 }

exercises/03_ticket_v1/11_destructor/src/lib.rs

@@ -2,7 +2,7 @@
 // We'll pick the concept up again in a later chapter after covering traits and
 // interior mutability.
 fn outro() -> &'static str {
-    "I have a basic understanding of __!"
+    "I have a basic understanding of destructors!"
 }
 
 #[cfg(test)]

exercises/03_ticket_v1/12_outro/src/lib.rs

@@ -11,3 +11,74 @@
 // Integration here has a very specific meaning: they test **the public API** of your project.
 // You'll need to pay attention to the visibility of your types and methods; integration
 // tests can't access private or `pub(crate)` items.
+pub struct Order {
+    product_name: String,
+    quantity: u32,
+    unit_price: u32,
+}
+
+impl Order {
+    pub fn new(product_name: String, quantity: u32, unit_price: u32) -> Order {
+        validate_product_name(&product_name);
+        validate_quantity(&quantity);
+        validate_unit_price(&unit_price);
+
+        Order {
+            product_name,
+            quantity,
+            unit_price,
+        }
+    }
+
+    pub fn product_name(&self) -> &String {
+        &self.product_name
+    }
+
+    pub fn quantity(&self) -> &u32 {
+        &self.quantity
+    }
+
+    pub fn unit_price(&self) -> &u32 {
+        &self.unit_price
+    }
+
+    pub fn set_product_name(&mut self, product_name: String) {
+        validate_product_name(&product_name);
+        self.product_name = product_name;
+    }
+
+    pub fn set_quantity(&mut self, quantity: u32) {
+        validate_quantity(&quantity);
+        self.quantity = quantity;
+    }
+
+    pub fn set_unit_price(&mut self, unit_price: u32) {
+        validate_unit_price(&unit_price);
+        self.unit_price = unit_price;
+    }
+
+    pub fn total(&self) -> u32 {
+        self.quantity * self.unit_price
+    }
+}
+
+fn validate_product_name(product_name: &String) {
+    if product_name.is_empty() {
+        panic!("Product name cannot be empty");
+    }
+    if product_name.len() > 300 {
+        panic!("Product name cannot be longer than 300 bytes");
+    }
+}
+
+fn validate_quantity(quantity: &u32) {
+    if quantity == &0 {
+        panic!("Quantity must be greater than zero");
+    }
+}
+
+fn validate_unit_price(unit_price: &u32) {
+    if unit_price == &0 {
+        panic!("Unit price must be greater than zero");
+    }
+}

exercises/04_traits/00_intro/src/lib.rs

@@ -1,6 +1,6 @@
 fn intro() -> &'static str {
     // TODO: fix me 👇
-    "I'm ready to __!"
+    "I'm ready to learn about traits!"
 }
 
 #[cfg(test)]

exercises/04_traits/01_trait/src/lib.rs

@@ -2,6 +2,21 @@
 // even, otherwise `false`.
 //
 // Then implement the trait for `u32` and `i32`.
+pub trait IsEven {
+    fn is_even(&self) -> bool;
+}
+
+impl IsEven for u32 {
+    fn is_even(&self) -> bool {
+        self % 2 == 0
+    }
+}
+
+impl IsEven for i32 {
+    fn is_even(&self) -> bool {
+        self % 2 == 0
+    }
+}
 
 #[cfg(test)]
 mod tests {

exercises/04_traits/02_orphan_rule/src/lib.rs

@@ -3,9 +3,3 @@
 //  a foreign type (`u32`, from `std`).
 //  Look at the compiler error to get familiar with what it looks like.
 //  Then delete the code below and move on to the next exercise.
-
-impl PartialEq for u32 {
-    fn eq(&self, _other: &Self) -> bool {
-        todo!()
-    }
-}

exercises/04_traits/03_operator_overloading/src/lib.rs

@@ -8,7 +8,13 @@ struct Ticket {
 
 // TODO: Implement the `PartialEq` trait for `Ticket`.
 
-impl PartialEq for Ticket {}
+impl PartialEq for Ticket {
+    fn eq(&self, other: &Self) -> bool {
+        self.title == other.title
+            && self.description == other.description
+            && self.status == other.status
+    }
+}
 
 #[cfg(test)]
 mod tests {

exercises/04_traits/04_derive/src/lib.rs

@@ -8,7 +8,7 @@
 // print both sides of the comparison to the terminal.
 // If the compared type doesn't implement `Debug`, it doesn't know how to represent them!
 
-#[derive(PartialEq)]
+#[derive(Debug, PartialEq)]
 struct Ticket {
     title: String,
     description: String,

exercises/04_traits/05_trait_bounds/src/lib.rs

@@ -6,7 +6,10 @@
 // collections (e.g. BTreeMap).
 
 /// Return the minimum of two values.
-pub fn min<T>(left: T, right: T) -> T {
+pub fn min<T: Ord>(left: T, right: T) -> T {
+    // `Ord` guarantees that the values can be compared.
+    // `PartialOrd` would also make the compiler happy, but it would have different semantics:
+    // it'd either return the minimum value or `right` if they can't be compared.
     if left <= right {
         left
     } else {

exercises/04_traits/06_str_slice/src/lib.rs

@@ -31,15 +31,15 @@ impl Ticket {
         }
     }
 
-    pub fn title(&self) -> &String {
+    pub fn title(&self) -> &str {
         &self.title
     }
 
-    pub fn description(&self) -> &String {
+    pub fn description(&self) -> &str {
         &self.description
     }
 
-    pub fn status(&self) -> &String {
+    pub fn status(&self) -> &str {
         &self.status
     }
 }

exercises/04_traits/07_deref/src/lib.rs

@@ -12,11 +12,11 @@ pub struct Ticket {
 
 impl Ticket {
     pub fn title(&self) -> &str {
-        todo!()
+        self.title.trim()
     }
 
     pub fn description(&self) -> &str {
-        todo!()
+        self.description.trim()
     }
 }
 

exercises/04_traits/08_sized/src/lib.rs

@@ -3,5 +3,5 @@ pub fn example() {
     // via `std::mem::size_of` will result in a compile-time error.
     //
     // TODO: Comment out the following line and move on to the next exercise.
-    std::mem::size_of::<str>();
+    // std::mem::size_of::<str>();
 }

exercises/04_traits/09_from/src/lib.rs

@@ -4,6 +4,12 @@ pub struct WrappingU32 {
     value: u32,
 }
 
+impl From<u32> for WrappingU32 {
+    fn from(value: u32) -> Self {
+        WrappingU32 { value }
+    }
+}
+
 fn example() {
     let wrapping: WrappingU32 = 42.into();
     let wrapping = WrappingU32::from(42);

exercises/04_traits/10_assoc_vs_generic/src/lib.rs

@@ -13,6 +13,36 @@
 // You don't have to though: it's perfectly okay to write three separate
 // implementations manually. Venture further only if you're curious.
 
+pub trait Power<Exponent = Self> {
+    type Output;
+
+    fn power(&self, n: Exponent) -> Self::Output;
+}
+
+impl Power<u16> for u32 {
+    type Output = u32;
+
+    fn power(&self, n: u16) -> Self::Output {
+        self.pow(n.into())
+    }
+}
+
+impl Power<&u32> for u32 {
+    type Output = u32;
+
+    fn power(&self, n: &u32) -> Self::Output {
+        self.power(*n)
+    }
+}
+
+impl Power<u32> for u32 {
+    type Output = u32;
+
+    fn power(&self, n: u32) -> Self::Output {
+        self.pow(n)
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::Power;

exercises/04_traits/11_clone/src/lib.rs

@@ -2,9 +2,10 @@
 //  to get the code to compile.
 
 pub fn summary(ticket: Ticket) -> (Ticket, Summary) {
-    (ticket, ticket.summary())
+    (ticket.clone(), ticket.summary())
 }
 
+#[derive(Clone)]
 pub struct Ticket {
     pub title: String,
     pub description: String,

exercises/04_traits/12_copy/src/lib.rs

@@ -1,6 +1,7 @@
 // TODO: implement the necessary traits to make the test compile and pass.
 //  You *can't* modify the test.
 
+#[derive(Debug, Clone, Copy, PartialEq)]
 pub struct WrappingU32 {
     value: u32,
 }
@@ -11,6 +12,14 @@ impl WrappingU32 {
     }
 }
 
+impl std::ops::Add for WrappingU32 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self::Output {
+        Self::new(self.value.wrapping_add(rhs.value))
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

exercises/04_traits/13_drop/src/lib.rs

@@ -1,6 +1,27 @@
 // TODO: implement a so-called "Drop bomb": a type that panics when dropped
 //  unless a certain operation has been performed on it.
 //  You can see the expected API in the tests below.
+pub struct DropBomb {
+    defused: bool,
+}
+
+impl DropBomb {
+    pub fn new() -> Self {
+        DropBomb { defused: false }
+    }
+
+    pub fn defuse(&mut self) {
+        self.defused = true;
+    }
+}
+
+impl Drop for DropBomb {
+    fn drop(&mut self) {
+        if !self.defused {
+            panic!("Boom!");
+        }
+    }
+}
 
 #[cfg(test)]
 mod tests {

exercises/04_traits/14_outro/src/lib.rs

@@ -8,3 +8,75 @@
 //   It should be possible to print its debug representation.
 //
 // Tests are located in the `tests` folder—pay attention to the visibility of your types and methods.
+
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub struct SaturatingU16 {
+    value: u16,
+}
+
+impl From<u16> for SaturatingU16 {
+    fn from(value: u16) -> Self {
+        Self { value }
+    }
+}
+
+impl From<u8> for SaturatingU16 {
+    fn from(value: u8) -> Self {
+        Self {
+            value: value.into(),
+        }
+    }
+}
+
+impl From<&u16> for SaturatingU16 {
+    fn from(value: &u16) -> Self {
+        (*value).into()
+    }
+}
+
+impl From<&u8> for SaturatingU16 {
+    fn from(value: &u8) -> Self {
+        (*value).into()
+    }
+}
+
+impl std::ops::Add for SaturatingU16 {
+    type Output = SaturatingU16;
+
+    fn add(self, rhs: Self) -> Self::Output {
+        self + rhs.value
+    }
+}
+
+impl std::ops::Add<&SaturatingU16> for SaturatingU16 {
+    type Output = SaturatingU16;
+
+    fn add(self, rhs: &SaturatingU16) -> Self::Output {
+        self + *rhs
+    }
+}
+
+impl std::ops::Add<u16> for SaturatingU16 {
+    type Output = Self;
+
+    fn add(self, rhs: u16) -> Self::Output {
+        let sum = self.value.saturating_add(rhs);
+        Self {
+            value: sum,
+        }
+    }
+}
+
+impl std::ops::Add<&u16> for SaturatingU16 {
+    type Output = SaturatingU16;
+
+    fn add(self, rhs: &u16) -> Self::Output {
+        self + *rhs
+    }
+}
+
+impl PartialEq<u16> for SaturatingU16 {
+    fn eq(&self, other: &u16) -> bool {
+        self.value == *other
+    }
+}

exercises/05_ticket_v2/00_intro/src/lib.rs

@@ -1,6 +1,6 @@
 fn intro() -> &'static str {
     // TODO: fix me 👇
-    "I'm ready to __!"
+    "I'm ready to refine the `Ticket` type!"
 }
 
 #[cfg(test)]

exercises/05_ticket_v2/01_enum/src/lib.rs

@@ -7,15 +7,18 @@
 struct Ticket {
     title: String,
     description: String,
-    status: String,
+    status: Status,
 }
 
+#[derive(Debug, PartialEq, Copy, Clone)]
 enum Status {
-    // TODO: add the missing variants
+    ToDo,
+    InProgress,
+    Done,
 }
 
 impl Ticket {
-    pub fn new(title: String, description: String, status: String) -> Ticket {
+    pub fn new(title: String, description: String, status: Status) -> Ticket {
         if title.is_empty() {
             panic!("Title cannot be empty");
         }
@@ -28,9 +31,6 @@ impl Ticket {
         if description.len() > 500 {
             panic!("Description cannot be longer than 500 bytes");
         }
-        if status != "To-Do" && status != "In Progress" && status != "Done" {
-            panic!("Only `To-Do`, `In Progress`, and `Done` statuses are allowed");
-        }
 
         Ticket {
             title,
@@ -47,7 +47,7 @@ impl Ticket {
         &self.description
     }
 
-    pub fn status(&self) -> &String {
+    pub fn status(&self) -> &Status {
         &self.status
     }
 }

exercises/05_ticket_v2/02_match/src/lib.rs

@@ -9,7 +9,12 @@ enum Shape {
 impl Shape {
     // TODO: Implement the `n_sides` method using a `match`.
     pub fn n_sides(&self) -> u8 {
-        todo!()
+        match self {
+            Shape::Circle => 0,
+            Shape::Square | Shape::Rectangle => 4,
+            Shape::Triangle => 3,
+            Shape::Pentagon => 5,
+        }
     }
 }
 

exercises/05_ticket_v2/03_variants_with_data/src/lib.rs

@@ -38,7 +38,10 @@ impl Ticket {
         }
     }
     pub fn assigned_to(&self) -> &str {
-        todo!()
+        match &self.status {
+            Status::InProgress { assigned_to } => assigned_to,
+            _ => panic!("Only `In-Progress` tickets can be assigned to someone"),
+        }
     }
 }
 

exercises/05_ticket_v2/04_if_let/src/lib.rs

@@ -8,7 +8,11 @@ impl Shape {
     // TODO: Implement the `radius` method using
     //  either an `if let` or a `let/else`.
     pub fn radius(&self) -> f64 {
-        todo!()
+        if let Shape::Circle { radius } = self {
+            *radius
+        } else {
+            panic!("Not a circle");
+        }
     }
 }
 

exercises/05_ticket_v2/05_nullability/src/lib.rs

@@ -36,7 +36,10 @@ impl Ticket {
         }
     }
     pub fn assigned_to(&self) -> Option<&String> {
-        todo!()
+        match &self.status {
+            Status::InProgress { assigned_to } => Some(assigned_to),
+            _ => None,
+        }
     }
 }
 

exercises/05_ticket_v2/06_fallibility/src/lib.rs

@@ -16,25 +16,25 @@ enum Status {
 }
 
 impl Ticket {
-    pub fn new(title: String, description: String, status: Status) -> Ticket {
+    pub fn new(title: String, description: String, status: Status) -> Result<Ticket, String> {
         if title.is_empty() {
-            panic!("Title cannot be empty");
+            return Err("Title cannot be empty".into());
         }
         if title.len() > 50 {
-            panic!("Title cannot be longer than 50 bytes");
+            return Err("Title cannot be longer than 50 bytes".into());
         }
         if description.is_empty() {
-            panic!("Description cannot be empty");
+            return Err("Description cannot be empty".into());
         }
         if description.len() > 500 {
-            panic!("Description cannot be longer than 500 bytes");
+            return Err("Description cannot be longer than 500 bytes".into());
         }
 
-        Ticket {
+        Ok(Ticket {
             title,
             description,
             status,
-        }
+        })
     }
 }
 

exercises/05_ticket_v2/07_unwrap/src/lib.rs

@@ -2,7 +2,16 @@
 //   When the description is invalid, instead, it should use a default description:
 //   "Description not provided".
 fn easy_ticket(title: String, description: String, status: Status) -> Ticket {
-    todo!()
+    match Ticket::new(title.clone(), description, status.clone()) {
+        Ok(ticket) => ticket,
+        Err(error) => {
+            if error.contains("Description") {
+                Ticket::new(title, "Description not provided".to_string(), status).unwrap()
+            } else {
+                panic!("{error}");
+            }
+        }
+    }
 }
 
 #[derive(Debug, PartialEq, Clone)]

exercises/05_ticket_v2/08_error_enums/src/lib.rs

@@ -1,14 +1,24 @@
 // TODO: Use two variants, one for a title error and one for a description error.
 //   Each variant should contain a string with the explanation of what went wrong exactly.
 //   You'll have to update the implementation of `Ticket::new` as well.
-enum TicketNewError {}
+#[derive(Debug)]
+enum TicketNewError {
+    TitleError(String),
+    DescriptionError(String),
+}
 
 // TODO: `easy_ticket` should panic when the title is invalid, using the error message
 //   stored inside the relevant variant of the `TicketNewError` enum.
 //   When the description is invalid, instead, it should use a default description:
 //   "Description not provided".
 fn easy_ticket(title: String, description: String, status: Status) -> Ticket {
-    todo!()
+    match Ticket::new(title.clone(), description, status.clone()) {
+        Ok(ticket) => ticket,
+        Err(TicketNewError::DescriptionError(_)) => {
+            Ticket::new(title, "Description not provided".to_string(), status).unwrap()
+        }
+        Err(TicketNewError::TitleError(error)) => panic!("{error}"),
+    }
 }
 
 #[derive(Debug, PartialEq)]
@@ -32,16 +42,24 @@ impl Ticket {
         status: Status,
     ) -> Result<Ticket, TicketNewError> {
         if title.is_empty() {
-            return Err("Title cannot be empty".to_string());
+            return Err(TicketNewError::TitleError(
+                "Title cannot be empty".to_string(),
+            ));
         }
         if title.len() > 50 {
-            return Err("Title cannot be longer than 50 bytes".to_string());
+            return Err(TicketNewError::TitleError(
+                "Title cannot be longer than 50 bytes".to_string(),
+            ));
         }
         if description.is_empty() {
-            return Err("Description cannot be empty".to_string());
+            return Err(TicketNewError::DescriptionError(
+                "Description cannot be empty".to_string(),
+            ));
         }
         if description.len() > 500 {
-            return Err("Description cannot be longer than 500 bytes".to_string());
+            return Err(TicketNewError::DescriptionError(
+                "Description cannot be longer than 500 bytes".to_string(),
+            ));
         }
 
         Ok(Ticket {

exercises/05_ticket_v2/09_error_trait/src/lib.rs

@@ -3,17 +3,37 @@
 //  The docs for the `std::fmt` module are a good place to start and look for examples:
 //  https://doc.rust-lang.org/std/fmt/index.html#write
 
+#[derive(Debug)]
 enum TicketNewError {
     TitleError(String),
     DescriptionError(String),
 }
 
+impl std::fmt::Display for TicketNewError {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        match self {
+            TicketNewError::TitleError(msg) => write!(f, "{}", msg),
+            TicketNewError::DescriptionError(msg) => write!(f, "{}", msg),
+        }
+    }
+}
+
+impl std::error::Error for TicketNewError {}
+
 // TODO: `easy_ticket` should panic when the title is invalid, using the error message
 //   stored inside the relevant variant of the `TicketNewError` enum.
 //   When the description is invalid, instead, it should use a default description:
 //   "Description not provided".
 fn easy_ticket(title: String, description: String, status: Status) -> Ticket {
-    todo!()
+    match Ticket::new(title.clone(), description, status.clone()) {
+        Ok(ticket) => ticket,
+        Err(err) => match err {
+            TicketNewError::TitleError(_) => panic!("{err}"),
+            TicketNewError::DescriptionError(_) => {
+                Ticket::new(title, "Description not provided".to_string(), status).unwrap()
+            }
+        },
+    }
 }
 
 #[derive(Debug, PartialEq, Clone)]

exercises/05_ticket_v2/10_packages/src/lib.rs

@@ -0,0 +1,3 @@
+pub fn hello_world() {
+    println!("Hello, world!");
+}

exercises/05_ticket_v2/11_dependencies/Cargo.toml

@@ -2,3 +2,6 @@
 name = "deps"
 version = "0.1.0"
 edition = "2021"
+
+[dependencies]
+anyhow = "1.0.82"

exercises/05_ticket_v2/12_thiserror/Cargo.toml

@@ -4,6 +4,7 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
+thiserror = "1"
 
 [dev-dependencies]
 common = { path = "../../../helpers/common" }

exercises/05_ticket_v2/12_thiserror/src/lib.rs

@@ -3,10 +3,15 @@
 //   a `String` field into each variant.
 //   You'll also have to add `thiserror` as a dependency in the `Cargo.toml` file.
 
+#[derive(Debug, thiserror::Error)]
 enum TicketNewError {
+    #[error("Title cannot be empty")]
     TitleCannotBeEmpty,
+    #[error("Title cannot be longer than 50 bytes")]
     TitleTooLong,
+    #[error("Description cannot be empty")]
     DescriptionCannotBeEmpty,
+    #[error("Description cannot be longer than 500 bytes")]
     DescriptionTooLong,
 }
 

exercises/05_ticket_v2/13_try_from/Cargo.toml

@@ -4,3 +4,4 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
+thiserror = "1.0.59"

exercises/05_ticket_v2/13_try_from/src/lib.rs

@@ -8,6 +8,35 @@ enum Status {
     Done,
 }
 
+#[derive(Debug, thiserror::Error)]
+#[error("{invalid_status} is not a valid status")]
+struct ParseStatusError {
+    invalid_status: String,
+}
+
+impl TryFrom<String> for Status {
+    type Error = ParseStatusError;
+
+    fn try_from(value: String) -> Result<Self, Self::Error> {
+        value.as_str().try_into()
+    }
+}
+
+impl TryFrom<&str> for Status {
+    type Error = ParseStatusError;
+
+    fn try_from(value: &str) -> Result<Self, Self::Error> {
+        match value.to_lowercase().as_str() {
+            "todo" => Ok(Status::ToDo),
+            "inprogress" => Ok(Status::InProgress),
+            "done" => Ok(Status::Done),
+            _ => Err(ParseStatusError {
+                invalid_status: value.to_string(),
+            }),
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

exercises/05_ticket_v2/14_source/src/lib.rs

@@ -1,4 +1,4 @@
-use crate::status::Status;
+use crate::status::{ParseStatusError, Status};
 
 // We've seen how to declare modules in one of the earliest exercises, but
 // we haven't seen how to extract them into separate files.
@@ -23,6 +23,8 @@ pub enum TicketNewError {
     DescriptionCannotBeEmpty,
     #[error("Description cannot be longer than 500 bytes")]
     DescriptionTooLong,
+    #[error("{0}")]
+    InvalidStatus(#[from] ParseStatusError),
 }
 
 #[derive(Debug, PartialEq, Clone)]
@@ -48,6 +50,7 @@ impl Ticket {
         }
 
         // TODO: Parse the status string into a `Status` enum.
+        let status = Status::try_from(status)?;
 
         Ok(Ticket {
             title,

exercises/05_ticket_v2/15_outro/Cargo.toml

@@ -2,3 +2,6 @@
 name = "outro_04"
 version = "0.1.0"
 edition = "2021"
+
+[dependencies]
+thiserror = "1.0.59"

exercises/05_ticket_v2/15_outro/src/description.rs

@@ -1,9 +1,45 @@
 // TODO: Implement `TryFrom<String>` and `TryFrom<&str>` for the `TicketDescription` type,
 //   enforcing that the description is not empty and is not longer than 500 bytes.
 //   Implement the traits required to make the tests pass too.
-
+#[derive(Debug, PartialEq, Clone)]
 pub struct TicketDescription(String);
 
+#[derive(Debug, thiserror::Error)]
+pub enum TicketDescriptionError {
+    #[error("The description cannot be empty")]
+    Empty,
+    #[error("The description cannot be longer than 500 bytes")]
+    TooLong,
+}
+
+impl TryFrom<String> for TicketDescription {
+    type Error = TicketDescriptionError;
+
+    fn try_from(value: String) -> Result<Self, Self::Error> {
+        validate(&value)?;
+        Ok(Self(value))
+    }
+}
+
+impl TryFrom<&str> for TicketDescription {
+    type Error = TicketDescriptionError;
+
+    fn try_from(value: &str) -> Result<Self, Self::Error> {
+        validate(value)?;
+        Ok(Self(value.to_string()))
+    }
+}
+
+fn validate(description: &str) -> Result<(), TicketDescriptionError> {
+    if description.is_empty() {
+        Err(TicketDescriptionError::Empty)
+    } else if description.len() > 500 {
+        Err(TicketDescriptionError::TooLong)
+    } else {
+        Ok(())
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

exercises/05_ticket_v2/15_outro/src/status.rs

@@ -1,12 +1,43 @@
 // TODO: Implement `TryFrom<String>` and `TryFrom<&str>` for the `Status` enum.
 //  The parsing should be case-insensitive.
 
+#[derive(Debug, PartialEq, Clone)]
 pub enum Status {
     ToDo,
     InProgress,
     Done,
 }
 
+impl TryFrom<String> for Status {
+    type Error = ParseStatusError;
+
+    fn try_from(value: String) -> Result<Self, Self::Error> {
+        let value = value.to_lowercase();
+        match value.as_str() {
+            "todo" => Ok(Status::ToDo),
+            "inprogress" => Ok(Status::InProgress),
+            "done" => Ok(Status::Done),
+            _ => Err(ParseStatusError {
+                invalid_status: value,
+            }),
+        }
+    }
+}
+
+impl TryFrom<&str> for Status {
+    type Error = ParseStatusError;
+
+    fn try_from(value: &str) -> Result<Self, Self::Error> {
+        value.to_lowercase().try_into()
+    }
+}
+
+#[derive(Debug, thiserror::Error)]
+#[error("`{invalid_status}` is not a valid status. Use one of: ToDo, InProgress, Done")]
+pub struct ParseStatusError {
+    invalid_status: String,
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

exercises/05_ticket_v2/15_outro/src/title.rs

@@ -2,8 +2,45 @@
 //   enforcing that the title is not empty and is not longer than 50 bytes.
 //   Implement the traits required to make the tests pass too.
 
+#[derive(Debug, PartialEq, Clone)]
 pub struct TicketTitle(String);
 
+#[derive(Debug, thiserror::Error)]
+pub enum TicketTitleError {
+    #[error("The title cannot be empty")]
+    Empty,
+    #[error("The title cannot be longer than 50 bytes")]
+    TooLong,
+}
+
+impl TryFrom<String> for TicketTitle {
+    type Error = TicketTitleError;
+
+    fn try_from(value: String) -> Result<Self, Self::Error> {
+        validate(&value)?;
+        Ok(Self(value))
+    }
+}
+
+impl TryFrom<&str> for TicketTitle {
+    type Error = TicketTitleError;
+
+    fn try_from(value: &str) -> Result<Self, Self::Error> {
+        validate(value)?;
+        Ok(Self(value.to_string()))
+    }
+}
+
+fn validate(title: &str) -> Result<(), TicketTitleError> {
+    if title.is_empty() {
+        Err(TicketTitleError::Empty)
+    } else if title.len() > 50 {
+        Err(TicketTitleError::TooLong)
+    } else {
+        Ok(())
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

exercises/06_ticket_management/00_intro/src/lib.rs

@@ -1,6 +1,6 @@
 fn intro() -> &'static str {
     // TODO: fix me 👇
-    "I'm ready to __!"
+    "I'm ready to build a ticket management system!"
 }
 
 #[cfg(test)]

exercises/06_ticket_management/01_arrays/src/lib.rs

@@ -1,7 +1,7 @@
 // TODO: Flesh out the `WeekTemperatures` struct and its method implementations to pass the tests.
 
 pub struct WeekTemperatures {
-    // TODO
+    temperatures: [Option<i32>; 7],
 }
 
 pub enum Weekday {
@@ -16,15 +16,31 @@ pub enum Weekday {
 
 impl WeekTemperatures {
     pub fn new() -> Self {
-        todo!()
+        WeekTemperatures {
+            temperatures: [None; 7],
+        }
     }
 
     pub fn get_temperature(&self, day: Weekday) -> Option<i32> {
-        todo!()
+        let index = weekday2index(&day);
+        self.temperatures[index]
     }
 
     pub fn set_temperature(&mut self, day: Weekday, temperature: i32) {
-        todo!()
+        let index = weekday2index(&day);
+        self.temperatures[index] = Some(temperature);
+    }
+}
+
+fn weekday2index(day: &Weekday) -> usize {
+    match day {
+        Weekday::Monday => 0,
+        Weekday::Tuesday => 1,
+        Weekday::Wednesday => 2,
+        Weekday::Thursday => 3,
+        Weekday::Friday => 4,
+        Weekday::Saturday => 5,
+        Weekday::Sunday => 6,
     }
 }
 

exercises/06_ticket_management/02_vec/src/lib.rs

@@ -11,11 +11,12 @@
 // We expect `fibonacci(0)` to return `0`, `fibonacci(1)` to return `1`,
 // `fibonacci(2)` to return `1`, and so on.
 pub fn fibonacci(n: u32) -> u32 {
-    // TODO: implement the `fibonacci` function
+    let n = n as usize;
-    //
+    let mut memo = vec![0, 1];
-    // Hint: use a `Vec` to memoize the results you have already calculated
+    for i in 2..=n {
-    // so that you don't have to recalculate them several times.
+        memo.push(memo[i - 1] + memo[i - 2]);
-    todo!()
+    }
+    memo[n]
 }
 
 #[cfg(test)]

exercises/06_ticket_management/03_resizing/src/lib.rs

@@ -12,6 +12,6 @@ mod tests {
         // Can you guess what the new capacity will be?
         // Beware that the standard library makes no guarantees about the
         // algorithm used to resize the vector, so this may change in the future.
-        assert_eq!(v.capacity(), todo!());
+        assert_eq!(v.capacity(), 4);
     }
 }

exercises/06_ticket_management/04_iterators/src/lib.rs

@@ -39,6 +39,15 @@ impl TicketStore {
     }
 }
 
+impl IntoIterator for TicketStore {
+    type Item = Ticket;
+    type IntoIter = std::vec::IntoIter<Self::Item>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.tickets.into_iter()
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

exercises/06_ticket_management/05_iter/src/lib.rs

@@ -34,6 +34,10 @@ impl TicketStore {
     pub fn add_ticket(&mut self, ticket: Ticket) {
         self.tickets.push(ticket);
     }
+
+    pub fn iter(&self) -> std::slice::Iter<Ticket> {
+        self.tickets.iter()
+    }
 }
 
 #[cfg(test)]

exercises/06_ticket_management/06_lifetimes/src/lib.rs

@@ -36,6 +36,15 @@ impl TicketStore {
     }
 }
 
+impl<'a> IntoIterator for &'a TicketStore {
+    type Item = &'a Ticket;
+    type IntoIter = std::slice::Iter<'a, Ticket>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.tickets.iter()
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

exercises/06_ticket_management/07_combinators/src/lib.rs

@@ -31,6 +31,13 @@ impl TicketStore {
     pub fn add_ticket(&mut self, ticket: Ticket) {
         self.tickets.push(ticket);
     }
+
+    pub fn to_dos(&self) -> Vec<&Ticket> {
+        self.tickets
+            .iter()
+            .filter(|ticket| ticket.status == Status::ToDo)
+            .collect()
+    }
 }
 
 #[cfg(test)]

exercises/06_ticket_management/08_impl_trait/src/lib.rs

@@ -31,6 +31,12 @@ impl TicketStore {
     pub fn add_ticket(&mut self, ticket: Ticket) {
         self.tickets.push(ticket);
     }
+
+    pub fn in_progress(&self) -> impl Iterator<Item = &Ticket> {
+        self.tickets
+            .iter()
+            .filter(|ticket| ticket.status == Status::InProgress)
+    }
 }
 
 #[cfg(test)]

exercises/06_ticket_management/09_impl_trait_2/src/lib.rs

@@ -33,7 +33,7 @@ impl TicketStore {
     // that can be infallibly converted into a `Ticket`.
     // This can make it nicer to use the method, as it removes the syntax noise of `.into()`
     // from the calling site. It can worsen the quality of the compiler error messages, though.
-    pub fn add_ticket(&mut self, ticket: impl Into<Ticket>) {
+    pub fn add_ticket<T: Into<Ticket>>(&mut self, ticket: T) {
         self.tickets.push(ticket.into());
     }
 }

exercises/06_ticket_management/10_slices/src/lib.rs

@@ -1,6 +1,10 @@
 // TODO: Define a function named `sum` that takes a reference to a slice of `u32` and returns the sum of all
 //  elements in the slice.
 
+pub fn sum(slice: &[u32]) -> u32 {
+    slice.iter().sum()
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

exercises/06_ticket_management/11_mutable_slices/src/lib.rs

@@ -1,6 +1,12 @@
 // TODO: Define a function named `squared` that raises all `i32`s within a slice to the power of 2.
 //  The slice should be modified in place.
 
+pub fn squared(slice: &mut [i32]) {
+    for i in slice.iter_mut() {
+        *i *= *i;
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

exercises/06_ticket_management/12_two_states/src/lib.rs

@@ -11,6 +11,7 @@ use ticket_fields::{TicketDescription, TicketTitle};
 #[derive(Clone)]
 pub struct TicketStore {
     tickets: Vec<Ticket>,
+    counter: u64,
 }
 
 #[derive(Clone, Copy, Debug, PartialEq)]
@@ -41,11 +42,25 @@ impl TicketStore {
     pub fn new() -> Self {
         Self {
             tickets: Vec::new(),
+            counter: 0,
         }
     }
 
-    pub fn add_ticket(&mut self, ticket: Ticket) {
+    pub fn add_ticket(&mut self, draft: TicketDraft) -> TicketId {
+        let id = self.counter;
+        self.counter += 1;
+        let ticket = Ticket {
+            id: TicketId(id),
+            title: draft.title,
+            description: draft.description,
+            status: Status::ToDo,
+        };
         self.tickets.push(ticket);
+        TicketId(id)
+    }
+
+    pub fn get(&self, id: TicketId) -> Option<&Ticket> {
+        self.tickets.iter().find(|ticket| ticket.id == id)
     }
 }
 

exercises/06_ticket_management/13_index/src/lib.rs

@@ -1,5 +1,6 @@
 // TODO: Implement `Index<&TicketId>` and `Index<TicketId>` for `TicketStore`.
 
+use std::ops::Index;
 use ticket_fields::{TicketDescription, TicketTitle};
 
 #[derive(Clone)]
@@ -58,6 +59,22 @@ impl TicketStore {
     }
 }
 
+impl Index<TicketId> for TicketStore {
+    type Output = Ticket;
+
+    fn index(&self, id: TicketId) -> &Self::Output {
+        self.tickets.iter().find(|&t| t.id == id).unwrap()
+    }
+}
+
+impl Index<&TicketId> for TicketStore {
+    type Output = Ticket;
+
+    fn index(&self, id: &TicketId) -> &Self::Output {
+        &self[*id]
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use crate::{Status, TicketDraft, TicketStore};

exercises/06_ticket_management/14_index_mut/src/lib.rs

@@ -1,6 +1,6 @@
 // TODO: Implement `IndexMut<&TicketId>` and `IndexMut<TicketId>` for `TicketStore`.
 
-use std::ops::Index;
+use std::ops::{Index, IndexMut};
 use ticket_fields::{TicketDescription, TicketTitle};
 
 #[derive(Clone)]
@@ -75,6 +75,18 @@ impl Index<&TicketId> for TicketStore {
     }
 }
 
+impl IndexMut<TicketId> for TicketStore {
+    fn index_mut(&mut self, index: TicketId) -> &mut Self::Output {
+        self.tickets.iter_mut().find(|t| t.id == index).unwrap()
+    }
+}
+
+impl IndexMut<&TicketId> for TicketStore {
+    fn index_mut(&mut self, index: &TicketId) -> &mut Self::Output {
+        &mut self[*index]
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use crate::{Status, TicketDraft, TicketStore};

exercises/06_ticket_management/15_hashmap/src/lib.rs

@@ -11,7 +11,7 @@ pub struct TicketStore {
     counter: u64,
 }
 
-#[derive(Clone, Copy, Debug, PartialEq)]
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
 pub struct TicketId(u64);
 
 #[derive(Clone, Debug, PartialEq)]
@@ -38,7 +38,7 @@ pub enum Status {
 impl TicketStore {
     pub fn new() -> Self {
         Self {
-            tickets: todo!(),
+            tickets: HashMap::new(),
             counter: 0,
         }
     }
@@ -52,16 +52,16 @@ impl TicketStore {
             description: ticket.description,
             status: Status::ToDo,
         };
-        todo!();
+        self.tickets.insert(id, ticket);
         id
     }
 
     pub fn get(&self, id: TicketId) -> Option<&Ticket> {
-        todo!()
+        self.tickets.get(&id)
     }
 
     pub fn get_mut(&mut self, id: TicketId) -> Option<&mut Ticket> {
-        todo!()
+        self.tickets.get_mut(&id)
     }
 }
 

exercises/06_ticket_management/16_btreemap/src/lib.rs

@@ -13,7 +13,7 @@ pub struct TicketStore {
     counter: u64,
 }
 
-#[derive(Clone, Copy, Debug, PartialEq)]
+#[derive(Clone, Copy, Debug, PartialEq, Ord, PartialOrd, Eq)]
 pub struct TicketId(u64);
 
 #[derive(Clone, Debug, PartialEq)]
@@ -40,7 +40,7 @@ pub enum Status {
 impl TicketStore {
     pub fn new() -> Self {
         Self {
-            tickets: todo!(),
+            tickets: BTreeMap::new(),
             counter: 0,
         }
     }
@@ -54,16 +54,16 @@ impl TicketStore {
             description: ticket.description,
             status: Status::ToDo,
         };
-        todo!();
+        self.tickets.insert(id, ticket);
         id
     }
 
     pub fn get(&self, id: TicketId) -> Option<&Ticket> {
-        todo!()
+        self.tickets.get(&id)
     }
 
     pub fn get_mut(&mut self, id: TicketId) -> Option<&mut Ticket> {
-        todo!()
+        self.tickets.get_mut(&id)
     }
 }
 
@@ -95,6 +95,15 @@ impl IndexMut<&TicketId> for TicketStore {
     }
 }
 
+impl<'a> IntoIterator for &'a TicketStore {
+    type Item = &'a Ticket;
+    type IntoIter = std::collections::btree_map::Values<'a, TicketId, Ticket>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.tickets.values()
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use crate::{Status, TicketDraft, TicketId, TicketStore};

exercises/07_threads/00_intro/src/lib.rs

@@ -1,6 +1,6 @@
 fn intro() -> &'static str {
     // TODO: fix me 👇
-    "I'm ready to _!"
+    "I'm ready to build a concurrent ticket management system!"
 }
 
 #[cfg(test)]

exercises/07_threads/01_threads/src/lib.rs

@@ -15,7 +15,15 @@
 use std::thread;
 
 pub fn sum(v: Vec<i32>) -> i32 {
-    todo!()
+    let mid = v.len() / 2;
+    let (v1, v2) = v.split_at(mid);
+    let v1 = v1.to_vec();
+    let v2 = v2.to_vec();
+
+    let handle1 = thread::spawn(move || v1.into_iter().sum::<i32>());
+    let handle2 = thread::spawn(move || v2.into_iter().sum::<i32>());
+
+    handle1.join().unwrap() + handle2.join().unwrap()
 }
 
 #[cfg(test)]

exercises/07_threads/02_static/src/lib.rs

@@ -4,7 +4,13 @@
 use std::thread;
 
 pub fn sum(slice: &'static [i32]) -> i32 {
-    todo!()
+    let mid = slice.len() / 2;
+    let (slice1, slice2) = slice.split_at(mid);
+
+    let handle1 = thread::spawn(move || slice1.iter().sum::<i32>());
+    let handle2 = thread::spawn(move || slice2.iter().sum::<i32>());
+
+    handle1.join().unwrap() + handle2.join().unwrap()
 }
 
 #[cfg(test)]

exercises/07_threads/03_leak/src/lib.rs

@@ -6,7 +6,14 @@
 use std::thread;
 
 pub fn sum(v: Vec<i32>) -> i32 {
-    todo!()
+    let v = v.leak();
+    let mid = v.len() / 2;
+    let (v1, v2) = v.split_at(mid);
+
+    let handle1 = thread::spawn(move || v1.into_iter().sum::<i32>());
+    let handle2 = thread::spawn(move || v2.into_iter().sum::<i32>());
+
+    handle1.join().unwrap() + handle2.join().unwrap()
 }
 
 #[cfg(test)]

exercises/07_threads/04_scoped_threads/src/lib.rs

@@ -3,7 +3,14 @@
 //  Don't perform any heap allocation. Don't leak any memory.
 
 pub fn sum(v: Vec<i32>) -> i32 {
-    todo!()
+    let mid = v.len() / 2;
+    let (left, right) = v.split_at(mid);
+
+    std::thread::scope(|s| {
+        let left = s.spawn(|| left.iter().sum::<i32>());
+        let right = s.spawn(|| right.iter().sum::<i32>());
+        left.join().unwrap() + right.join().unwrap()
+    })
 }
 
 #[cfg(test)]

exercises/07_threads/05_channels/src/lib.rs

@@ -1,10 +1,12 @@
+use crate::data::TicketDraft;
+use crate::store::TicketStore;
 use std::sync::mpsc::{Receiver, Sender};
 
 pub mod data;
 pub mod store;
 
 pub enum Command {
-    Insert(todo!()),
+    Insert(TicketDraft),
 }
 
 // Start the system by spawning the server thread.
@@ -20,4 +22,13 @@ pub fn launch() -> Sender<Command> {
 //  Enter a loop: wait for a command to show up in
 //  the channel, then execute it, then start waiting
 //  for the next command.
-pub fn server(receiver: Receiver<Command>) {}
+pub fn server(receiver: Receiver<Command>) {
+    let mut store = TicketStore::new();
+    while let Ok(command) = receiver.recv() {
+        match command {
+            Command::Insert(ticket_draft) => {
+                store.add_ticket(ticket_draft);
+            }
+        }
+    }
+}

exercises/07_threads/05_channels/tests/insert.rs

@@ -26,7 +26,7 @@ fn ready() {
     // since our server doesn't expose any **read** actions.
     // We have no way to know if the inserts are actually happening and if they
     // are happening correctly.
-    let move_forward = false;
+    let move_forward = true;
 
     assert!(move_forward);
 }

exercises/07_threads/06_interior_mutability/src/lib.rs

@@ -6,18 +6,18 @@ use std::rc::Rc;
 
 pub struct DropTracker<T> {
     value: T,
-    counter: todo!(),
+    counter: Rc<RefCell<usize>>,
 }
 
 impl<T> DropTracker<T> {
-    pub fn new(value: T, counter: todo!()) -> Self {
+    pub fn new(value: T, counter: Rc<RefCell<usize>>) -> Self {
         Self { value, counter }
     }
 }
 
 impl<T> Drop for DropTracker<T> {
     fn drop(&mut self) {
-        todo!()
+        *self.counter.borrow_mut() += 1;
     }
 }
 

exercises/07_threads/07_ack/src/lib.rs

@@ -1,13 +1,20 @@
+use crate::data::{Ticket, TicketDraft};
+use crate::store::{TicketId, TicketStore};
 use std::sync::mpsc::{Receiver, Sender};
-use crate::store::TicketStore;
 
 pub mod data;
 pub mod store;
 
 // Refer to the tests to understand the expected schema.
 pub enum Command {
-    Insert { todo!() },
+    Insert {
-    Get { todo!() }
+        draft: TicketDraft,
+        response_sender: Sender<TicketId>,
+    },
+    Get {
+        id: TicketId,
+        response_sender: Sender<Option<Ticket>>,
+    },
 }
 
 pub fn launch() -> Sender<Command> {
@@ -21,19 +28,25 @@ pub fn server(receiver: Receiver<Command>) {
     let mut store = TicketStore::new();
     loop {
         match receiver.recv() {
-            Ok(Command::Insert {}) => {
+            Ok(Command::Insert {
-                todo!()
+                draft,
+                response_sender,
+            }) => {
+                let id = store.add_ticket(draft);
+                let _ = response_sender.send(id);
             }
             Ok(Command::Get {
-                todo!()
+                id,
+                response_sender,
             }) => {
-                todo!()
+                let ticket = store.get(id);
+                let _ = response_sender.send(ticket.cloned());
             }
             Err(_) => {
                 // There are no more senders, so we can safely break
                 // and shut down the server.
-                break
+                break;
-            },
+            }
         }
     }
 }

exercises/07_threads/08_client/src/lib.rs

@@ -7,23 +7,39 @@ pub mod store;
 
 #[derive(Clone)]
 // TODO: flesh out the client implementation.
-pub struct TicketStoreClient {}
+pub struct TicketStoreClient {
+    sender: Sender<Command>,
+}
 
 impl TicketStoreClient {
     // Feel free to panic on all errors, for simplicity.
     pub fn insert(&self, draft: TicketDraft) -> TicketId {
-        todo!()
+        let (response_sender, response_receiver) = std::sync::mpsc::channel();
+        self.sender
+            .send(Command::Insert {
+                draft,
+                response_channel: response_sender,
+            })
+            .unwrap();
+        response_receiver.recv().unwrap()
     }
 
     pub fn get(&self, id: TicketId) -> Option<Ticket> {
-        todo!()
+        let (response_sender, response_receiver) = std::sync::mpsc::channel();
+        self.sender
+            .send(Command::Get {
+                id,
+                response_channel: response_sender,
+            })
+            .unwrap();
+        response_receiver.recv().unwrap()
     }
 }
 
 pub fn launch() -> TicketStoreClient {
     let (sender, receiver) = std::sync::mpsc::channel();
     std::thread::spawn(move || server(receiver));
-    todo!()
+    TicketStoreClient { sender }
 }
 
 // No longer public! This becomes an internal detail of the library now.

exercises/07_threads/09_bounded/Cargo.toml

@@ -4,4 +4,5 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
+thiserror = "1.0.60"
 ticket_fields = { path = "../../../helpers/ticket_fields" }

exercises/07_threads/09_bounded/src/lib.rs

@@ -1,44 +1,62 @@
 // TODO: Convert the implementation to use bounded channels.
 use crate::data::{Ticket, TicketDraft};
 use crate::store::{TicketId, TicketStore};
-use std::sync::mpsc::{Receiver, Sender};
+use std::sync::mpsc::{Receiver, Sender, SyncSender, TrySendError};
 
 pub mod data;
 pub mod store;
 
 #[derive(Clone)]
 pub struct TicketStoreClient {
-    sender: todo!(),
+    sender: SyncSender<Command>,
 }
 
 impl TicketStoreClient {
-    pub fn insert(&self, draft: TicketDraft) -> Result<TicketId, todo!()> {
+    pub fn insert(&self, draft: TicketDraft) -> Result<TicketId, OverloadedError> {
-        todo!()
+        let (response_sender, response_receiver) = std::sync::mpsc::sync_channel(1);
+        self.sender
+            .try_send(Command::Insert {
+                draft,
+                response_channel: response_sender,
+            })
+            .map_err(|_| OverloadedError)?;
+        Ok(response_receiver.recv().unwrap())
     }
 
-    pub fn get(&self, id: TicketId) -> Result<Option<Ticket>, todo!()> {
+    pub fn get(&self, id: TicketId) -> Result<Option<Ticket>, OverloadedError> {
-        todo!()
+        let (response_sender, response_receiver) = std::sync::mpsc::sync_channel(1);
+        self.sender
+            .try_send(Command::Get {
+                id,
+                response_channel: response_sender,
+            })
+            .map_err(|_| OverloadedError)?;
+        Ok(response_receiver.recv().unwrap())
     }
 }
 
+#[derive(Debug, thiserror::Error)]
+#[error("The store is overloaded")]
+pub struct OverloadedError;
+
 pub fn launch(capacity: usize) -> TicketStoreClient {
-    todo!();
+    let (sender, receiver) = std::sync::mpsc::sync_channel(capacity);
     std::thread::spawn(move || server(receiver));
-    todo!()
+    TicketStoreClient { sender }
 }
 
 enum Command {
     Insert {
         draft: TicketDraft,
-        response_channel: todo!(),
+        response_channel: SyncSender<TicketId>,
     },
     Get {
         id: TicketId,
-        response_channel: todo!(),
+        response_channel: SyncSender<Option<Ticket>>,
     },
 }
 
-pub fn server(receiver: Receiver<Command>) {
+fn server(receiver: Receiver<Command>) {
     let mut store = TicketStore::new();
     loop {
         match receiver.recv() {
@@ -47,14 +65,14 @@ pub fn server(receiver: Receiver<Command>) {
                 response_channel,
             }) => {
                 let id = store.add_ticket(draft);
-                todo!()
+                let _ = response_channel.send(id);
             }
             Ok(Command::Get {
                 id,
                 response_channel,
             }) => {
                 let ticket = store.get(id);
-                todo!()
+                let _ = response_channel.send(ticket.cloned());
             }
             Err(_) => {
                 // There are no more senders, so we can safely break

exercises/07_threads/10_patch/src/lib.rs

@@ -35,7 +35,16 @@ impl TicketStoreClient {
         Ok(response_receiver.recv().unwrap())
     }
 
-    pub fn update(&self, ticket_patch: TicketPatch) -> Result<(), OverloadedError> {}
+    pub fn update(&self, ticket_patch: TicketPatch) -> Result<(), OverloadedError> {
+        let (response_sender, response_receiver) = sync_channel(1);
+        self.sender
+            .try_send(Command::Update {
+                patch: ticket_patch,
+                response_channel: response_sender,
+            })
+            .map_err(|_| OverloadedError)?;
+        Ok(response_receiver.recv().unwrap())
+    }
 }
 
 #[derive(Debug, thiserror::Error)]
@@ -85,7 +94,18 @@ pub fn server(receiver: Receiver<Command>) {
                 patch,
                 response_channel,
             }) => {
-                todo!()
+                if let Some(ticket) = store.get_mut(patch.id) {
+                    if let Some(title) = patch.title {
+                        ticket.title = title;
+                    }
+                    if let Some(description) = patch.description {
+                        ticket.description = description;
+                    }
+                    if let Some(status) = patch.status {
+                        ticket.status = status;
+                    }
+                }
+                let _ = response_channel.send(());
             }
             Err(_) => {
                 // There are no more senders, so we can safely break

exercises/07_threads/11_locks/src/store.rs

@@ -28,13 +28,13 @@ impl TicketStore {
             description: ticket.description,
             status: Status::ToDo,
         };
-        todo!();
+        self.tickets.insert(id, Arc::new(Mutex::new(ticket)));
         id
     }
 
     // The `get` method should return a handle to the ticket
     // which allows the caller to either read or modify the ticket.
-    pub fn get(&self, id: TicketId) -> Option<todo!()> {
+    pub fn get(&self, id: TicketId) -> Option<Arc<Mutex<Ticket>>> {
-        todo!()
+        self.tickets.get(&id).cloned()
     }
 }

exercises/07_threads/12_rw_lock/src/lib.rs

@@ -1,7 +1,7 @@
+use std::sync::{Arc, Mutex, RwLock};
 // TODO: Replace `Mutex` with `RwLock` in the `TicketStore` struct and
 //  all other relevant places to allow multiple readers to access the ticket store concurrently.
-use std::sync::mpsc::{sync_channel, Receiver, SyncSender, TrySendError};
+use std::sync::mpsc::{sync_channel, Receiver, SyncSender};
-use std::sync::{Arc, Mutex};
 
 use crate::data::{Ticket, TicketDraft};
 use crate::store::{TicketId, TicketStore};
@@ -26,7 +26,7 @@ impl TicketStoreClient {
         Ok(response_receiver.recv().unwrap())
     }
 
-    pub fn get(&self, id: TicketId) -> Result<Option<Arc<Mutex<Ticket>>>, OverloadedError> {
+    pub fn get(&self, id: TicketId) -> Result<Option<Arc<RwLock<Ticket>>>, OverloadedError> {
         let (response_sender, response_receiver) = sync_channel(1);
         self.sender
             .try_send(Command::Get {
@@ -55,7 +55,7 @@ enum Command {
     },
     Get {
         id: TicketId,
-        response_channel: SyncSender<Option<Arc<Mutex<Ticket>>>>,
+        response_channel: SyncSender<Option<Arc<RwLock<Ticket>>>>,
     },
 }
 

exercises/07_threads/12_rw_lock/src/store.rs

@@ -1,13 +1,13 @@
 use crate::data::{Status, Ticket, TicketDraft};
 use std::collections::BTreeMap;
-use std::sync::{Arc, Mutex};
+use std::sync::{Arc, RwLock};
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
 pub struct TicketId(u64);
 
 #[derive(Clone)]
 pub struct TicketStore {
-    tickets: BTreeMap<TicketId, Arc<Mutex<Ticket>>>,
+    tickets: BTreeMap<TicketId, Arc<RwLock<Ticket>>>,
     counter: u64,
 }
 
@@ -28,14 +28,14 @@ impl TicketStore {
             description: ticket.description,
             status: Status::ToDo,
         };
-        let ticket = Arc::new(Mutex::new(ticket));
+        let ticket = Arc::new(RwLock::new(ticket));
         self.tickets.insert(id, ticket);
         id
     }
 
     // The `get` method should return a handle to the ticket
     // which allows the caller to either read or modify the ticket.
-    pub fn get(&self, id: TicketId) -> Option<Arc<Mutex<Ticket>>> {
+    pub fn get(&self, id: TicketId) -> Option<Arc<RwLock<Ticket>>> {
         self.tickets.get(&id).cloned()
     }
 }

exercises/07_threads/13_without_channels/tests/check.rs

@@ -7,7 +7,7 @@ use without_channels::store::TicketStore;
 
 #[test]
 fn works() {
-    let store = todo!();
+    let store = Arc::new(RwLock::new(TicketStore::new()));
 
     let store1 = store.clone();
     let client1 = spawn(move || {

exercises/07_threads/14_sync/src/lib.rs

@@ -1,6 +1,6 @@
 // Not much to be exercised on `Sync`, just a thing to remember.
 fn outro() -> &'static str {
-    "I have a good understanding of __!"
+    "I have a good understanding of Send and Sync!"
 }
 
 #[cfg(test)]

exercises/08_futures/00_intro/src/lib.rs

@@ -1,6 +1,6 @@
 fn intro() -> &'static str {
     // TODO: fix me 👇
-    "I'm ready to _!"
+    "I'm ready to learn about futures!"
 }
 
 #[cfg(test)]

exercises/08_futures/01_async_fn/src/lib.rs

@@ -11,7 +11,11 @@ use tokio::net::TcpListener;
 // - `tokio::net::TcpStream::split` to obtain a reader and a writer from the socket
 // - `tokio::io::copy` to copy data from the reader to the writer
 pub async fn echo(listener: TcpListener) -> Result<(), anyhow::Error> {
-    todo!()
+    loop {
+        let (mut socket, _) = listener.accept().await?;
+        let (mut reader, mut writer) = socket.split();
+        tokio::io::copy(&mut reader, &mut writer).await?;
+    }
 }
 
 #[cfg(test)]