print_matrix.py

def main():
    assert gen_matrix(4, 3) == [[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12]]
    print_matrix(gen_matrix(4, 6))

# 1, 2, 3, 4, 8, 12, 11, 10, 9, 5, 6, 7


def gen_matrix(width, height):
    ret = [range(1 + width * ih, 1 + width * (ih + 1)) for ih in range(height)]
    return ret


DIRECTIONS = range(4)
GO_RIGHT, GO_DOWN, GO_LEFT, GO_UP = DIRECTIONS


def print_matrix(sequences):
    if not sequences:
        return  # nothing to print
    width = len(sequences[0])
    height = len(sequences)

    min_iw, min_ih = 0, 0
    max_iw, max_ih = width - 1, height - 1

    S, di, i, total = sequences, 0, 0, (width * height)
    while i < total:
        cur_dir = di % len(DIRECTIONS)
        if cur_dir == GO_RIGHT:
            for iw in range(min_iw, max_iw + 1):
                i += 1
                print S[min_ih][iw]
            min_ih += 1
        elif cur_dir == GO_DOWN:
            for ih in range(min_ih, max_ih + 1):
                i += 1
                print S[ih][max_iw]
            max_iw -= 1
        elif cur_dir == GO_LEFT:
            for iw in range(max_iw, min_iw - 1, -1):
                i += 1
                print S[max_ih][iw]
            max_ih -= 1
        elif cur_dir == GO_UP:
            for ih in range(max_ih, min_ih - 1, -1):
                i += 1
                print S[ih][min_iw]
            min_iw += 1
        di += 1
    return


# TODO: is there a analytical way to know the ending coordinates


if __name__ == '__main__':
    main()