[LeetCode]189. Rotate Array

Problem Description

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].

思路

先翻转整个数组，再翻转两个部分！！

Code

package q189;

public class Solution {

public static void rotate(int[] nums, int k) {
if(nums.length<2) return;
while(nums.length<k){
k=k-nums.length;
}
helper(nums,0,nums.length-1);
helper(nums,0,k-1);
helper(nums,k,nums.length-1);
}

public static void helper(int[] nums,int begin,int end){
while(begin<end){
nums[begin]=nums[begin]^nums[end];
nums[end]=nums[begin]^nums[end];
nums[begin]=nums[begin]^nums[end];
begin++;
end--;
}

}

//  public static void main(String[] args) {
//      int[] a={1,2,3,4,5,6,7};
//      rotate(a,11);
//      for(int i=0;i<a.length;i++){
//          System.out.print(a[i]+" ");
//      }
//  }

}