def rotate(self, matrix: List[List[int]]) -> None:
    def transpose():
        for row in range(n):
            for col in range(row+1, n):
                matrix[row][col], matrix[col][row] = matrix[col][row], matrix[row][col]

    def reflect():
        for row in range(n):
            for col in range(n // 2):
                matrix[row][col], matrix[row][-col-1] = matrix[row][-col-1], matrix[row][col]

    n = len(matrix)
    transpose()
    reflect()
    return