原题传送门->189. Rotate Array

Description

Given an array, rotate the array to the right by k steps, where k is non-negative.

Follow up:

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?

Example 1:

Input: nums = [1,2,3,4,5,6,7], 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: nums = [-1,-100,3,99], 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]

Constraints:

1 <= nums.length <= 2e4
-2^31 <= nums[i] <= 2^31 - 1
0 <= k <= 1e5

简单的数组操作。

class Solution {
public:
    void rotate(vector<int>& nums, int k) {
        int step = k % nums.size();
        vector<int> res;
        for(int i = 0; i < step; ++i) {
            res.push_back(nums[nums.size()-step+i]);
        }
        for(int i = nums.size()-1; i >= step; --i){
            nums[i] = nums[i-step];
        }
        for(int i = 0; i < step; ++i){
            nums[i] = res[i];
        }
    }
};