48. 旋转图像

给定一个 × n 的二维矩阵表示一个图像。

将图像顺时针旋转 90 度。

说明:

你必须在原地旋转图像,这意味着你需要直接修改输入的二维矩阵。请不要使用另一个矩阵来旋转图像。

示例 1:

给定 matrix = 
[
  [1,2,3],
  [4,5,6],
  [7,8,9]
],

原地旋转输入矩阵,使其变为:
[
  [7,4,1],
  [8,5,2],
  [9,6,3]
]

示例 2给定 matrix =

[
  [ 5, 1, 9,11],
  [ 2, 4, 8,10],
  [13, 3, 6, 7],
  [15,14,12,16]
], 

原地旋转输入矩阵,使其变为:
[
  [15,13, 2, 5],
  [14, 3, 4, 1],
  [12, 6, 8, 9],
  [16, 7,10,11]
]


normal solution
class Solution:
    def rotate(self, matrix: List[List[int]]) -> None:
        """
        Do not return anything, modify matrix in-place instead.
        """
        n = len(matrix)
        for i in range(n//2):
            for j in range (n):
                matrix[i][j] ,matrix[n - i - 1][j] = matrix[n - i - 1][j],matrix[i][j]
        for i in range(n):
            for j in range(i, n):
                matrix[i][j], matrix[j][i] =  matrix[j][i] , matrix[i][j]

lazy solution

class Solution:
    def rotate(self, matrix: List[List[int]]) -> None:
        """
        Do not return anything, modify matrix in-place instead.
        """
        matrix[:] = map(list, zip(*matrix[::-1]))
[
  [1,2,3],
  [4,5,6],
  [7,8,9]
],
------>>>>
[
  [7,8,9],
  [4,5,6],
  [1,2,3]
],
------>>>>
[
  [7,4,1],
  [8,5,2],
  [9,6,3]
]
原文地址:https://www.cnblogs.com/xxxsans/p/14158136.html