problem:
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?
thinking:
(1)题目要求原址操作
(2)先将矩阵 转置,再将矩阵沿中间对称左右翻转
code:
class Solution { public: void rotate(vector<vector<int> > &matrix) { int dim = matrix.size(); int temp = 0; for (int i = 0; i < dim; ++i) { //转置 for (int j = i+1; j < dim; ++j) { temp = matrix[i][j]; matrix[i][j] = matrix[j][i]; matrix[j][i] = temp; } } for (int i = 0; i < dim/2; ++i) { //对称变换 for (int j = 0; j < dim; ++j) { temp = matrix[j][i]; matrix[j][i] = matrix[j][dim - i -1]; matrix[j][dim - i -1] = temp; } } } };
原文地址:http://blog.csdn.net/hustyangju/article/details/44753005