LeetCode: 48. Rotate Image

Rotating a matrix 90 degrees clockwise can be achieved just by transposing + mirror reversing.

class Solution:
    def rotate(self, matrix: List[List[int]]) -> None:
        """
        Do not return anything, modify matrix in-place instead.
        """
        m, n = len(matrix), len(matrix[0])
        for i in range(m):
            for j in range(i+1, n):
                matrix[i][j], matrix[j][i] = matrix[j][i], matrix[i][j]
        
        for i in range(m):
            for j in range(n//2):
                matrix[i][j], matrix[i][n-j-1] = matrix[i][n-j-1], matrix[i][j]