题目来源
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?
题意分析
Input:a matrix represented with list[list[]]
Output:a matrix
Conditions:rotate 90 degrees clockwise
题目思路
注意到是将原来的矩阵顺时针旋转90度，本来直接转换比较费劲，网上大神说先转置然后每一行reverse即得所求，仔细观察矩阵的构造，的确如此，代码就几行……注意观察，不一定要一步得出答案。
AC代码（Python）
1 _author_ = "YE" 2 # -*- coding:utf-8 -*- 3 4 class Solution(object): 5 def rotate(self, matrix): 6 """ 7 :type matrix: List[List[int]] 8 :rtype: void Do not return anything, modify matrix in-place instead. 9 """ 10 n = len(matrix) 11 for i in range(n): 12 for j in range(i + 1, n): 13 matrix[i][j], matrix[j][i] = matrix[j][i], matrix[i][j] 14 15 for i in range(n): 16 matrix[i].reverse() 17 18 s = Solution() 19 f = [[1,2,3], 20 [4,5,6], 21 [7,8,9]] 22 23 print(s.rotate(f)) 24 print(f)
[LeetCode]题解（python）：048-Rotate Image
原文：http://www.cnblogs.com/loadofleaf/p/5052011.html