[LeetCode]189.Rotate Array

题目

Rotate an array of n elements to the right by k steps.

For example, with n = 7 and k = 3, the array [1,2,3,4,5,6,7] is rotated to [5,6,7,1,2,3,4].

Note: Try to come up as many solutions as you can, there are at least 3 different ways to solve this problem.

Hint: Could you do it in-place with O(1) extra space?

思路一

跟字符串左右旋转操作一样的思路。 三次翻转法，，第一次翻转前n-k个，第二次翻转后k个，第三次翻转全部。

代码一

/*——————————————–* 日期：2014-02-25* 作者：SJF0115* 题目: 189.Rotate Array* 网址：https://oj.leetcode.com/problems/rotate-array/* 结果：AC* 来源：LeetCode* 博客：————————————————*/;class Solution {public:void rotate(int nums[], int n, int k) {if(n <= 1){return;}//ifk = k % n;if(k <= 0){return;}//if// 翻转前n-k个Reverse(nums,0,n – k – 1);// 翻转后k个Reverse(nums,n – k,n – 1);// 翻转全部Reverse(nums,0,n – 1);}private:void Reverse(int nums[],int left,int right){int tmp;for(int i = left,j = right;i < j;++i,–j){// 交换swap(nums[i],nums[j]);}//for}};int main() {Solution solution;int A[] = {1,2,3,4,5,6,7};int n = 7;int k = 2;solution.rotate(A,n,k);for(int i = 0;i < n;++i){cout<<A[i]<<” “;}//forcout<<endl;return 0;}

去旅行不在于记忆，而在于当时的那份心情。