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?
题目大意：
给定一个数组，将数组“右移”k位。
理 解：
以数组[1,2,3,4,5,6,7]和k=3为例，右移3位结果为[5,6,7,1,2,3,4]。
把数组分为两个部分，左边0到n-k-1为一部分，n-k 到n为另一部分。
分别逆置两部分元素，结果为[4,3,2,1,7,6,5]；再逆置整个数组，结果为[5,6,7,1,2,3,4]。
代 码 C++：
class Solution { public: void rotate(vector<int>& nums, int k) { int n = nums.size(); if(k>=n) k = k%n; reverse(nums.begin(),nums.begin()+n-k); reverse(nums.begin()+n-k,nums.end()); reverse(nums.begin(),nums.end()); } };
运行结果：
执行用时 :44 ms, 在所有C++提交中击败了40.35%的用户
内存消耗 :9.6 MB, 在所有C++提交中击败了14.06%的用户