描述
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?
分析
将矩阵顺时针旋转90°，等同于先沿水平中线翻转，再按主对角线翻转。
代码
Python
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| class Solution(object):
def rotate(self, matrix):
"""
:type matrix: List[List[int]]
:rtype: void Do not return anything, modify matrix in-place instead.
"""
n = len(matrix)
for i in xrange(n / 2):
for j in xrange(n):
matrix[i][j], matrix[n - 1 - i][j] = matrix[n - 1 - i][j], matrix[i][j]
for i in xrange(n):
for j in xrange(i):
matrix[i][j], matrix[j][i] = matrix[j][i], matrix[i][j]
|