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?
矩阵的旋转
如
1 2 3
4 5 6
7 8 9
顺时针旋转90度为
7 4 1
8 5 2
9 6 3
（i,j）旋转后变成 (j,n-i-1)
class Solution { public: void rotate(vector<vector<int> > &matrix) { int n = matrix.size(); for(int i = 0 ;i < n/2; ++ i){ for(int j = i; j < n - i-1; ++ j){ swap(matrix[i][j],matrix[j][n-i-1]); swap(matrix[i][j],matrix[n-i-1][n-j-1]); swap(matrix[i][j],matrix[n-j-1][i]); } } } };
Leetcode Rotate Image,布布扣,bubuko.com
原文：http://www.cnblogs.com/xiongqiangcs/p/3815243.html