189.rotate-array.js

/*
 * @lc app=leetcode id=189 lang=javascript
 *
 * [189] Rotate Array
 *
 * https://leetcode.com/problems/rotate-array/description/
 *
 * algorithms
 * Easy (29.07%)
 * Total Accepted:    287.3K
 * Total Submissions: 966.9K
 * Testcase Example:  '[1,2,3,4,5,6,7]\n3'
 *
 * 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.
 */
var rotate = function(nums, k) {
  // 就像扩容一样操作
  k = k % nums.length;
  const n = nums.length;

  for (let i = nums.length - 1; i >= 0; i--) {
    nums[i + k] = nums[i];
  }

  for (let i = 0; i < k; i++) {
    nums[i] = nums[n + i];
  }
  nums.length = n;
};