Merge pull request #108 from jsca-kwok/jk-shuffle-array

Add shuffle array algorithm

DIRECTORY.md

@@ -16,6 +16,7 @@
     * [Remove Elements](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/arrays/remove_elements.rb)
     * [Richest Customer Wealth](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/arrays/richest_customer_wealth.rb)
     * [Single Number](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/arrays/single_number.rb)
+    * [Shuffle Array](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/arrays/shuffle_array.rb)
     * [Sort Squares Of An Array](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/arrays/sort_squares_of_an_array.rb)
     * [Two Sum](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/arrays/two_sum.rb)
     * [Two Sum Ii](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/arrays/two_sum_ii.rb)

data_structures/arrays/shuffle_array.rb

@@ -0,0 +1,109 @@
+# Challenge name: Shuffle the array
+#
+# Given the array nums consisting of 2n elements
+# in the form [x1,x2,...,xn,y1,y2,...,yn].
+# Return the array in the form [x1,y1,x2,y2,...,xn,yn].
+#
+# Example 1:
+# Input: nums = [2,5,1,3,4,7], n = 3
+# Output: [2,3,5,4,1,7]
+# Explanation: Since x1=2, x2=5, x3=1, y1=3, y2=4, y3=7 then the answer is [2,3,5,4,1,7].
+#
+# Example 2:
+# Input: nums = [1,2,3,4,4,3,2,1], n = 4
+# Output: [1,4,2,3,3,2,4,1]
+#
+# Example 3:
+# Input: nums = [1,1,2,2], n = 2
+# Output: [1,2,1,2]
+#
+# @param {Integer[]} nums
+# @param {Integer} n
+# @return {Integer[]}
+
+#
+# Approach 1: New Array
+#
+# Time Complexity: O(N)
+#
+def shuffle(nums, n)
+  result = []
+  (0..n-1).count do |i|
+    result.push(nums[i], nums[i+n])
+  end
+  result
+end
+
+nums = [2, 5, 1, 3, 4, 7]
+n = 3
+print(shuffle(nums, n))
+# Output: [2,3,5,4,1,7]
+nums = [1, 2, 3, 4, 4, 3, 2, 1]
+n = 4
+print(shuffle(nums, n))
+# Output: [1,4,2,3,3,2,4,1]
+nums = [1, 1, 2, 2]
+n = 2
+print(shuffle(nums, n))
+# Output: [1,2,1,2]
+
+#
+# Approach 2: Use Ruby methods .insert() and .delete_at()
+#
+# Time Complexity: O(N)
+#
+
+def shuffle(nums, n)
+  current_index = 1
+  (0..n-1).each do |i|
+    nums.insert(current_index, nums.delete_at(i + n))
+    current_index += 2
+  end
+  nums
+end
+
+nums = [2, 5, 1, 3, 4, 7]
+n = 3
+print(shuffle(nums, n))
+# Output: [2,3,5,4,1,7]
+nums = [1, 2, 3, 4, 4, 3, 2, 1]
+n = 4
+print(shuffle(nums, n))
+# Output: [1,4,2,3,3,2,4,1]
+nums = [1, 1, 2, 2]
+n = 2
+print(shuffle(nums, n))
+# Output: [1,2,1,2]
+
+#
+# Approach 3: Two Pointers
+#
+# Time Complexity: O(N)
+#
+
+def shuffle(nums, n)
+  result = []
+  p1 = 0
+  p2 = n
+
+  while p1 < n
+    result.push(nums[p1], nums[p2])
+    p1 +=1
+    p2 +=1
+  end
+
+  result
+end
+
+nums = [2, 5, 1, 3, 4, 7]
+n = 3
+print(shuffle(nums, n))
+# Output: [2,3,5,4,1,7]
+nums = [1, 2, 3, 4, 4, 3, 2, 1]
+n = 4
+print(shuffle(nums, n))
+# Output: [1,4,2,3,3,2,4,1]
+nums = [1, 1, 2, 2]
+n = 2
+print(shuffle(nums, n))
+# Output: [1,2,1,2]