[leetcode] Rotate Image

From : https://leetcode.com/problems/rotate-image/

You are given an n x n 2D matrix representing an image.

Rotate the image by 90 degrees (clockwise).

Follow up:
Could you do this in-place?

class Solution {public:    void rotate(vector<vector<int>>& matrix) {        int n= matrix.size();        for(int i=0, lst=(1+n)/2; i<lst; i++) {            for(int j=i; j<n-i-1; j++) {                int t = matrix[i][j];                matrix[i][j] = matrix[n-1-j][i];                matrix[n-1-j][i] = matrix[n-1-i][n-1-j];                matrix[n-1-i][n-1-j] = matrix[j][n-1-i];                matrix[j][n-1-i] = t;            }        }    }};

public class Solution {    public void rotate(int[][] matrix) {        if(null == matrix || null == matrix[0]) {            return;        }        int n = matrix.length;        if(n <= 1 || matrix[0].length != n) {            return;        }        for(int i=0, N=n-1; i<(n>>1); ++i) {            for(int j=i; j<N-i; ++j) {                int t = matrix[i][j];                matrix[i][j] = matrix[N-j][i];                matrix[N-j][i] = matrix[N-i][N-j];                matrix[N-i][N-j] = matrix[j][N-i];                matrix[j][N-i] = t;            }        }    }}