Merge pull request #146 from TheAlgorithms/remove_project_euler

remove `project_euler`

CONTRIBUTING.md

@@ -50,7 +50,6 @@ Algorithms in this repo should not be how-to examples for existing Ruby packages
 
 #### Other Requirements for Submissions
 
-- If you are submitting code in the `project_euler/` directory, please also read [the dedicated Guideline](https://github.com/TheAlgorithms/Ruby/blob/master/project_euler/README.md) before contributing to our Project Euler library.
 - Strictly use snake_case (underscore_separated) in your file_name, as it will be easy to parse in future using scripts.
 - Please avoid creating new directories if at all possible. Try to fit your work into the existing directory structure.
 - If possible, follow the standard *within* the folder you are submitting to.

DIRECTORY.md

@@ -103,26 +103,6 @@
 ## Other
   * [Fisher Yates](https://github.com/TheAlgorithms/Ruby/blob/master/other/fisher_yates.rb)
 
-## Project Euler
-  * Problem 1
-    * [Sol1](https://github.com/TheAlgorithms/Ruby/blob/master/project_euler/problem_1/sol1.rb)
-  * Problem 2
-    * [Sol1](https://github.com/TheAlgorithms/Ruby/blob/master/project_euler/problem_2/sol1.rb)
-  * Problem 20
-    * [Sol1](https://github.com/TheAlgorithms/Ruby/blob/master/project_euler/problem_20/sol1.rb)
-  * Problem 21
-    * [Sol1](https://github.com/TheAlgorithms/Ruby/blob/master/project_euler/problem_21/sol1.rb)
-  * Problem 22
-    * [Sol1](https://github.com/TheAlgorithms/Ruby/blob/master/project_euler/problem_22/sol1.rb)
-  * Problem 3
-    * [Sol1](https://github.com/TheAlgorithms/Ruby/blob/master/project_euler/problem_3/sol1.rb)
-    * [Sol2](https://github.com/TheAlgorithms/Ruby/blob/master/project_euler/problem_3/sol2.rb)
-  * Problem 4
-    * [Sol1](https://github.com/TheAlgorithms/Ruby/blob/master/project_euler/problem_4/sol1.rb)
-    * [Sol2](https://github.com/TheAlgorithms/Ruby/blob/master/project_euler/problem_4/sol2.rb)
-  * Problem 5
-    * [Sol1](https://github.com/TheAlgorithms/Ruby/blob/master/project_euler/problem_5/sol1.rb)
-
 ## Searches
   * [Binary Search](https://github.com/TheAlgorithms/Ruby/blob/master/searches/binary_search.rb)
   * [Depth First Search](https://github.com/TheAlgorithms/Ruby/blob/master/searches/depth_first_search.rb)

project_euler/README.md

@@ -1,20 +0,0 @@
-# Project Euler
-
-Problems are taken from https://projecteuler.net/, the Project Euler. [Problems are licensed under CC BY-NC-SA 4.0](https://projecteuler.net/copyright).
-
-Project Euler is a series of challenging mathematical/computer programming problems that require more than just mathematical
-insights to solve. Project Euler is ideal for mathematicians who are learning to code.
-
-## Solution Guidelines
-
-Welcome to [TheAlgorithms/Ruby](https://github.com/TheAlgorithms/Ruby)! Before reading the solution guidelines, make sure you read the whole [Contributing Guidelines](https://github.com/TheAlgorithms/Ruby/blob/master/CONTRIBUTING.md) as it won't be repeated in here. If you have any doubt on the guidelines, please feel free to [state it clearly in an issue](https://github.com/TheAlgorithms/Ruby/issues/new) or ask the community in [Gitter](https://gitter.im/TheAlgorithms). Be sure to read the [Coding Style](https://github.com/TheAlgorithms/Ruby/blob/master/project_euler/README.md#coding-style) before starting solution.
-
-### Coding Style
-
-* Please maintain consistency in project directory and solution file names. Keep the following points in mind:
-  * Create a new directory only for the problems which do not exist yet.
-  * Please name the project **directory** as `problem_<problem_number>` where `problem_number` should be filled with 0s so as to occupy 3 digits. Example: `problem_001`, `problem_002`, `problem_067`, `problem_145`, and so on.
-
-* You can have as many helper functions as you want but there should be one main function called `solution` which should satisfy the conditions as stated below:
-  * It should contain positional argument(s) whose default value is the question input. Example: Please take a look at [Problem 1](https://projecteuler.net/problem=1) where the question is to *Find the sum of all the multiples of 3 or 5 below 1000.* In this case the main solution function will be `solution(limit = 1000)`.
-  * When the `solution` function is called without any arguments like so: `solution()`, it should return the answer to the problem.

project_euler/problem_1/sol1.rb

@@ -1,14 +0,0 @@
-# If we list all the natural numbers below 10 that are multiples of 3 or 5,
-# we get 3, 5, 6 and 9. The sum of these multiples is 23.
-# Find the sum of all the multiples of 3 or 5 below 1000.
-
-def divisible_by_three_or_five?(number)
-  (number % 3).zero? || (number % 5).zero?
-end
-
-sum = 0
-(1...1000).each do |i|
-  sum += i if divisible_by_three_or_five?(i)
-end
-
-p sum

project_euler/problem_2/sol1.rb

@@ -1,17 +0,0 @@
-# Each new term in the Fibonacci sequence is generated by adding the previous two terms.
-# By starting with 1 and 2, the first 10 terms will be:
-#                                           1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...
-# By considering the terms in the Fibonacci sequence whose values do not exceed four million,
-# find the sum of the even-valued terms.
-
-even_fib_sum = 0
-fib_first = 1
-fib_second = 2
-
-while fib_second < 4_000_000
-  even_fib_sum += fib_second if fib_second.even?
-  fib_second += fib_first
-  fib_first = fib_second - fib_first
-end
-
-p even_fib_sum

project_euler/problem_20/sol1.rb

@@ -1,18 +0,0 @@
-# frozen_string_literal: true
-
-# n! means n x (n - 1) x ... x 3 x 2 x 1
-
-# For example, 10! = 10 x 9 x ... x 3 x 2 x 1 = 3628800,
-# and the sum of the digits in the number 10! is 3 + 6 + 2 + 8 + 8 + 0 + 0 = 27.
-#
-# Find the sum of the digits in the number 100!
-
-# method to calculate factorial of a number
-def factorial(number)
-  number.downto(1).reduce(:*)
-end
-
-# fetch digits of factorial of `number` and find
-# sum of all those digits, and prints the result on the console
-number = 100
-puts factorial(number).digits.sum

project_euler/problem_21/sol1.rb

@@ -1,57 +0,0 @@
-# frozen_string_literal: true
-
-# Let d(n) be defined as the sum of proper divisors of n
-# (numbers less than n which divide evenly into n).
-# If d(a) = b and d(b) = a, where a & b, then a and b are an amicable pair.
-# and each of a and b are called amicable numbers.
-#
-# For example,
-#
-# The proper divisors of 220 are 1, 2, 4, 5, 10, 11, 20, 22, 44, 55 and 110;
-# therefore d(220) = 284.
-#
-# The proper divisors of 284 are 1, 2, 4, 71 and 142; so d(284) = 220.
-#
-# Evaluate the sum of all the amicable numbers under 10000.
-
-# get list of all divisors of `number`
-def get_divisors(number)
-  divisors = []
-  (1..(Math.sqrt(number).to_i)).each do |num|
-    if (number % num).zero?
-      divisors << num
-      divisors << number / num
-    end
-  end
-  divisors
-end
-
-# get list of all proper divisors of `number` i.e. removing `number` from
-# the list of divisors
-def get_proper_divisors(number)
-  divisors = get_divisors(number)
-  divisors.delete(number)
-  divisors
-end
-
-# implementation of a method `d` as mentioned in the question
-# i.e. finding sum of all proper divisors of `number`
-def d(number)
-  get_proper_divisors(number).sum
-end
-
-# given an upper `limit`, this method finds all amicable numbers
-# under this `limit`
-def find_amicable_numbers(limit)
-  result = []
-  (1...limit).each do |a|
-    b = d(a)
-    res = d(b)
-    result.push(a) if (a == res) && (a != b)
-  end
-  result
-end
-
-# calling `find_amicable_numbers` method and finding sum of all such numbers
-# below 10000, and printing the result on the console
-puts find_amicable_numbers(10_000).sum

project_euler/problem_22/sol1.rb

@@ -1,40 +0,0 @@
-# frozen_string_literal: true
-
-# Problem 22
-# Using names.txt (right click and 'Save Link/Target As...'),
-# a 46K text file containing over five-thousand first names,
-# begin by sorting it into alphabetical order.
-# Then working out the alphabetical value for each name,
-# multiply this value by its alphabetical position in the list to obtain a name score.
-
-# For example, when the list is sorted into alphabetical order,
-# COLIN, which is worth 3 + 15 + 12 + 9 + 14 = 53,
-# is the 938th name in the list. So, COLIN would obtain a score of 938 * 53 = 49714.
-
-# What is the total of all the name scores in the file?
-
-# reading the contents of the file
-file_contents = File.read('p022_names.txt')
-
-# replacing the occuerance of \" to '' and spliting the result by ','
-# to get an array of sorted words
-words = file_contents.tr('\"', '').split(',').sort
-
-# this method calculates the worth of a word based on the ASCII
-# values of the characters
-def word_worth(word)
-  word.chars.sum { |char| char.ord - 'A'.ord + 1 }
-end
-
-# this method takes the words as an input
-# calls `word_worth` method on each word
-# to that value multiply that with the index of the word in the array
-# add the same to the result
-def total_rank(words)
-  result = 0
-  words.each_with_index { |word, index| result += word_worth(word) * (index + 1) }
-  result
-end
-
-# outputs total rank on the console
-puts total_rank(words)

project_euler/problem_3/sol1.rb

@@ -1,29 +0,0 @@
-# frozen_string_literal: true
-
-# The prime factors of 13195 are 5, 7, 13 and 29.
-# What is the largest prime factor of the number 600851475143
-
-# find all factors of the given number
-def get_factors(number)
-  factors = []
-  (1..Math.sqrt(number).to_i).each do |num|
-    if (number % num).zero?
-      factors << num
-      factors << number / num
-    end
-  end
-  factors
-end
-
-# determine if a given number is a prime number
-def prime?(number)
-  get_factors(number).length == 2
-end
-
-# find the largest prime
-def largest_prime_factor(number)
-  prime_factors = get_factors(number).select { |factor| prime?(factor) }
-  prime_factors.max
-end
-
-puts largest_prime_factor(600_851_475_143)

project_euler/problem_3/sol2.rb

@@ -1,18 +0,0 @@
-# The prime factors of 13195 are 5, 7, 13 and 29.
-# What is the largest prime factor of the number 600851475143 ?
-
-def solution(n)
-  prime = 1
-  i = 2
-  while i * i <= n
-    while (n % i).zero?
-      prime = i
-      n = n.fdiv i
-    end
-    i += 1
-  end
-  prime = n if n > 1
-  prime.to_i
-end
-
-puts solution(600_851_475_143)

project_euler/problem_4/sol1.rb

@@ -1,11 +0,0 @@
-# A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 × 99.
-# Find the largest palindrome made from the product of two 3-digit numbers.
-
-answer = 0
-999.downto(99) do |i|
-  999.downto(99) do |j|
-    t = (i * j)
-    answer = i * j if (t.to_s == t.to_s.reverse) && (t > answer) && (t > answer)
-  end
-end
-puts answer

project_euler/problem_4/sol2.rb

@@ -1,26 +0,0 @@
-# frozen_string_literal: true
-
-# A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 × 99.
-# Find the largest palindrome made from the product of two 3-digit numbers.
-
-class Integer
-  def parindrome?
-    self == reverse
-  end
-
-  # 123.reverse == 321
-  # 100.reverse == 1
-  def reverse
-    result = 0
-    n = self
-    loop do
-      result = result * 10 + n % 10
-      break if (n /= 10).zero?
-    end
-    result
-  end
-end
-
-factors = (100..999).to_a
-products = factors.product(factors).map { _1 * _2 }
-puts products.select(&:parindrome?).max

project_euler/problem_5/sol1.rb

@@ -1,22 +0,0 @@
-# 2520 is the smallest number that can be divided
-# by each of the numbers from 1 to 10 without any remainder.
-# What is the smallest positive number that is evenly
-# divisible by all of the numbers from 1 to 20?
-
-# Euclid's algorithm for the greatest common divisor
-def gcd(a, b)
-  b.zero? ? a : gcd(b, a % b)
-end
-
-# Calculate the LCM using GCD
-def lcm(a, b)
-  (a * b) / gcd(a, b)
-end
-
-result = 1
-
-20.times do |i|
-  result = lcm(result, i + 1)
-end
-
-p result