def rotate_matrix(matrix):
    n = len(matrix)
    res = [[None] * n] * n

    for n_row in range(n):
        for n_col in range(n):
            res[n_row][n_col] = matrix[n - n_col -1][n_row]
    return res

test = [[1, 2, 3, 4, 5],
        [6, 7, 8, 9, 10],
        [11, 12, 13, 14, 15],
        [16, 17, 18, 19, 20],
        [21, 22, 23, 24, 25]]

print(rotate_matrix(test))

# [[25, 20, 15, 10, 5],
#  [25, 20, 15, 10, 5],
#  [25, 20, 15, 10, 5],
#  [25, 20, 15, 10, 5],
#  [25, 20, 15, 10, 5]]