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?
思路：先将矩阵转置，然后将第一列与最后一列替换，第二列与倒数第二列替换。。一次类推。。即可得到
public class Solution { public void rotate(int[][] matrix) { int n = matrix.length; for(int i=1;i<n;i++){ for(int j=0;j<i;j++){ int temp = matrix[i][j]; matrix[i][j]=matrix[j][i]; matrix[j][i]=temp; } } for(int m=0;m<n/2;m++){ for(int mm=0;mm<n;mm++){ int temp = matrix[mm][m]; matrix[mm][m]=matrix[mm][n-m-1]; matrix[mm][n-m-1]=temp; } } } }
【LeetCode】Rotate Image,布布扣,bubuko.com
原文：http://www.cnblogs.com/yixianyixian/p/3722091.html