0189. Rotate Array.js

// Given an array, rotate the array to the right by k steps, where k is non-negative.
//
// Example 1:
//
// Input: [1,2,3,4,5,6,7] and k = 3
// Output: [5,6,7,1,2,3,4]
// Explanation:
//   rotate 1 steps to the right: [7,1,2,3,4,5,6]
//   rotate 2 steps to the right: [6,7,1,2,3,4,5]
//   rotate 3 steps to the right: [5,6,7,1,2,3,4]
//
// Example 2:
//
// Input: [-1,-100,3,99] and k = 2
// Output: [3,99,-1,-100]
// Explanation:
//   rotate 1 steps to the right: [99,-1,-100,3]
//   rotate 2 steps to the right: [3,99,-1,-100]
//
// Note:
//
//   Try to come up as many solutions as you can, there are at least 3 different ways to solve this problem.
//   Could you do it in-place with O(1) extra space?

/**
 * @param {number[]} nums
 * @param {number} k
 * @return {void} Do not return anything, modify nums in-place instead.
 */

// 1)
const rotate1 = (nums, k) => {
  for (let i = 0; i < k; i++) {
    nums.unshift(nums.pop());
  }
};

// 2)
const rotate = (nums, k) => {
  nums.unshift(...nums.splice(nums.length - k, k)); // splice mutates original array, and also return removed items
};