Q16.js

// 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]

// Constraints:

// 1 <= n <= 500
// nums.length == 2n
// 1 <= nums[i] <= 10^3

//  * @param {number[]} nums
//  * @param {number} n
//  * @return {number[]}

var shuffle = function (nums, n) {
  let x = [];
  let y = [];
  let count = 0;
  for (let i = n; i < 2 * n; i++) {
    y[count] = nums[i];
    count++;
  }
  for (let i = 0; i < n; i++) {
    x[i] = nums[i];
  }
  count = 0;
  nums[0] = x[0];
  nums[1] = y[1];

  for (let i = 0; i < 2 * n; i+=2) {
    nums[i] = x[count];
    count++;
  }
  count = 0;
  for (let i = 1; i < 2 * n; i+=2) {
    nums[i] = y[count];
    count++;
  }

  return nums;
};

console.log(shuffle([1, 1, 2, 2], 2))