Rotate Array

public class Solution {
    public void rotate(int[] nums, int k) {
        if(nums==null||nums.length<2||k<1) return;
        int n = nums.length;
        k = (int) k%n;
        for(int i=0;i<(n-k)/2;i++){
            swap(nums, i, n-k-i-1);
        }
        for(int i = n-k; i<n-k+k/2; i++){
            swap(nums,i,n-1-i+n-k); // 这里容易错
        }
        for(int i=0;i<n/2;i++){
            swap(nums,i,n-1-i);
        }
    }
    public void swap(int[] n, int i, int j){
        int t = n[j];
        n[j] = n[i];
        n[i] = t;
    }
}