912. Sort an Array

README.md

@@ -42,7 +42,8 @@
 | 652 | Find Duplicate Subtrees | [Ruby](./algorithms/ruby/0652-find-duplicate-subtrees.rb) | Medium |
 | 733 | Flood Fill | [Ruby](./algorithms/ruby/0733-flood-fill.rb) | Easy |
 | 783 | Minimum Distance Between BST Nodes | [Ruby](./algorithms/ruby/0783-minimum-distance-between-bst-nodes.rb) [Python3](./algorithms/python3/0783-minimum-distance-between-bst-nodes.py) | Easy |
-| 904 | Fruit Into Baskets | [Ruby](./algorithms/ruby/0904-fruit-into-baskets:description.rb) | Medium |
+| 904 | Fruit Into Baskets | [Ruby](./algorithms/ruby/0904-fruit-into-baskets.rb) | Medium |
+| 912 | Sort an Array | [Ruby](./algorithms/ruby/0912-sort-an-array.rb) | Medium |
 | 953 | Verifying an Alien Dictionary | [Ruby](./algorithms/ruby/0953-verifying-an-alien-dictionary.rb) | Easy |
 | 989 | Add to Array-Form of Integer | [Ruby](./algorithms/ruby/0989-add-to-array-form-of-integer.rb) | Easy |
 | 990 | Satisfiability of Equality Equations | [Ruby](./algorithms/ruby/0990-satisfiability-of-equality-equations.rb) | Medium |

algorithms/ruby/0912-sort-an-array.rb

@@ -0,0 +1,50 @@
+# frozen_string_literal: true
+
+# Problem: 912. Sort an Array
+# URL: https://leetcode.com/problems/sort-an-array
+
+# @param {Integer[]} nums
+# @return {Integer[]}
+def sort_array(nums)
+ in_place_quick_sort(nums, 0, nums.length - 1)
+ nums
+end
+
+def in_place_quick_sort(nums, l, r)
+ return if l >= r
+
+ pivot = nums[rand(l..r)]
+ pl, pr = partition(nums, l, r, pivot)
+ in_place_quick_sort(nums, l, pl - 1)
+ in_place_quick_sort(nums, pr + 1, r)
+end
+
+def partition(nums, l, r, pivot)
+ p0, p1, p2 = l, l, r
+ while p1 <= p2
+ if nums[p1] < pivot
+ nums[p0], nums[p1] = nums[p1], nums[p0]
+ p0 += 1
+ p1 += 1
+ elsif nums[p1] == pivot
+ p1 += 1
+ else
+ nums[p1], nums[p2] = nums[p2], nums[p1]
+ p2 -= 1
+ end
+ end
+
+ [p0, p2]
+end
+
+# ********************#
+# TEST #
+# ********************#
+
+require "test/unit"
+class Test_sort_array < Test::Unit::TestCase
+ def test_
+ assert_equal [1, 2, 3, 5], sort_array([5, 2, 3, 1])
+ assert_equal [0, 0, 1, 1, 2, 5], sort_array([5, 1, 1, 2, 0, 0])
+ end
+end