题目：
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?
public class Solution {
public void rotate(int[][] matrix) {
int n=matrix.length;
for (int i = 0; i < n/2; i++) {
for (int j = i; j <n-i-1 ; j++) {
int tmpValue1=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]=tmpValue1;
}
}
}
}
public class Solution {
public void rotate(int[][] matrix) {
int n=matrix.length;
for (int i = 0; i < n/2; i++) {
for (int j = i; j <n-i-1 ; j++) {
int tmpValue1=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]=tmpValue1;
}
}
}
}
原文：https://www.cnblogs.com/xww115/p/11232130.html