problem_065.py

def get_spiral(matrix, srow, scol, erow, ecol):
    numbers = list()
    for i in range(scol, ecol + 1):
        numbers.append(matrix[srow][i])

    for i in range(srow + 1, erow + 1):
        numbers.append(matrix[i][ecol])

    if srow < erow:
        for i in range(ecol - 1, srow - 1, -1):
            numbers.append(matrix[erow][i])

    if scol < ecol:
        for i in range(erow - 1, srow, -1):
            numbers.append(matrix[i][scol])

    return numbers


def spiral_helper(matrix):
    srow, scol, erow, ecol = 0, 0, len(matrix) - 1, len(matrix[0]) - 1
    clockwise_numbers = list()
    while srow < erow or scol < ecol:
        clockwise_numbers.extend(get_spiral(matrix, srow, scol, erow, ecol))
        if srow < erow:
            srow += 1
            erow -= 1
        if scol < ecol:
            scol += 1
            ecol -= 1

    return clockwise_numbers


matrix_0 = [[1,  2,  3,  4,  5],
            [6,  7,  8,  9,  10],
            [11, 12, 13, 14, 15],
            [16, 17, 18, 19, 20]]
assert spiral_helper(matrix_0) == [
    1, 2, 3, 4, 5, 10, 15, 20, 19, 18, 17, 16, 11, 6, 7, 8, 9, 14, 13, 12]

matrix_1 = [[1,  2,  3],
            [6,  7,  8],
            [11, 12, 13],
            [16, 17, 18]]
assert spiral_helper(matrix_1) == [
    1, 2, 3, 8, 13, 18, 17, 16, 11, 6, 7, 12]

matrix_2 = [[1, 4], [2, 5], [3, 6]]
assert spiral_helper(matrix_2) == [1, 4, 5, 6, 3, 2]

matrix_3 = [[1, 2, 3]]
assert spiral_helper(matrix_3) == [1, 2, 3]

matrix_4 = [[1], [2], [3]]
assert spiral_helper(matrix_4) == [1, 2, 3]