leetcode--Rotate Array

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.

题意：旋转数组，给定数组长度n，k表示从右向左数k个数，将这k个数旋转到数组前面

分类：数组

解法1：三次反转数组即可。首先反转0到n-k-1，再反转n-k到n-1，最后将整个数组反转

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1. public class Solution {  
2.     public void rotate(int[] nums, int k) {  
3.         if(nums.length==k) return;//k等于数组长度，直接返回  
4.         if(nums.length<k) k = k%nums.length;//k大于数组长度，取k%nums.length  
5.         rotate(nums, 0, nums.length-1-k);  
6.         rotate(nums, nums.length-k, nums.length-1);  
7.         rotate(nums, 0, nums.length-1);  
8.     }  
9.       
10.     public void rotate(int[] nums,int i,int j){  
11.         while(i<j){  
12.             int t = nums[i];  
13.             nums[i] = nums[j];  
14.             nums[j] = t;  
15.             i++;j--;  
16.         }  
17.     }  
18. }  

原文链接http://blog.youkuaiyun.com/crazy__chen/article/details/45440869