48. Rotate Image

Medium

You are given an n x n 2D matrix representing an image. Rotate the image by 90 degrees (clockwise). Note: You have to rotate the image in-place, which means you have to modify the input 2D matrix directly. DO NOT allocate another 2D matrix and do the rotation.

😇 Solution

O(mn)

class Solution:
    def rotate(self, matrix: List[List[int]]) -> None:
        """
        Do not return anything, modify matrix in-place instead.
        """
        a = matrix
        n = len(a)
        for i in range(n):
            for j in range(n):
                if(i<j):
                    a[i][j],a[j][i] = a[j][i],a[i][j]
        for a1 in a:
            a1.reverse()