Merge pull request #95 from TheAlgorithms/find-the-highest-altitude

Find the Highest Altitude

DIRECTORY.md

@@ -5,6 +5,7 @@
 ## Data Structures
   * Arrays
     * [Find All Duplicates In An Array](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/arrays/find_all_duplicates_in_an_array.rb)
+    * [Find The Highest Altitude](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/arrays/find_the_highest_altitude.rb)
     * [Get Products Of All Other Elements](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/arrays/get_products_of_all_other_elements.rb)
   * Binary Trees
     * [Inorder Traversal](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/binary_trees/inorder_traversal.rb)

data_structures/arrays/find_the_highest_altitude.rb

@@ -0,0 +1,74 @@
+# Find the Highest Altitude
+
+# There is a biker going on a road trip. The road trip
+# consists of n + 1 points at different altitudes. The
+# biker starts his trip on point 0 with altitude equal 0.
+
+# You are given an integer array gain of length n where
+# gain[i] is the net gain in altitude between points i​​​​​​
+# and i + 1 for all (0 <= i < n).
+
+# Return the highest altitude of a point.
+
+# Example 1:
+#
+# Input: gain = [-5,1,5,0,-7]
+# Output: 1
+# Explanation: The altitudes are [0,-5,-4,1,1,-6].
+# The highest is 1.
+#
+
+#
+# Approach 1: Creating an additional array
+#
+
+# @param {Integer[]} gain
+# @return {Integer}
+def largest_altitude(gain)
+  arr = [0]
+
+  # calculate altitude array
+  (1..gain.count).each do |pointer|
+    sum = arr[pointer - 1] + gain[pointer - 1]
+    arr.push(sum)
+  end
+
+  # find maximum altitude
+  max = 0
+  arr.each { |i| max = i if max < i }
+  max
+end
+
+gain = [-5, 1, 5, 0, -7]
+largest_altitude(gain)
+# Output: 1
+
+gain = [-4, -3, -2, -1, 4, 3, 2]
+largest_altitude(gain)
+# Output: 0
+
+#
+# Approach 2: Without creating an additional array
+#
+
+# @param {Integer[]} gain
+# @return {Integer}
+def largest_altitude(gain)
+  max_alt = alt = 0
+
+  (0...gain.count).each do |i|
+    alt += gain[i]
+
+    max_alt = alt if max_alt < alt
+  end
+
+  max_alt
+end
+
+gain = [-5, 1, 5, 0, -7]
+largest_altitude(gain)
+# Output: 1
+
+gain = [-4, -3, -2, -1, 4, 3, 2]
+largest_altitude(gain)
+# Output: 0