spiral print

spiral.py

"""
    Print a matrix m x n following sprial-in clockwise direction from top left
    Example:
        matrix:
            1 2 3 4 5 6 7 8
            9 0 1 2 3 4 5 6
            7 8 9 0 1 2 3 4
            5 6 7 8 9 0 1 2
        sprial print:
            1 2 3 4 5 6 7 8 6 4 2 1 0 9 8 7 6 5 7 9 0 1 2 3 4 5 3 2 1 0 9 8
"""


def print_ltr(matrix, r):
    r.extend(matrix[0])
    return matrix[1:]


def print_ttb(matrix, r):
    r.extend([row[-1] for row in matrix])
    return [row[:len(matrix[0])-1] for row in matrix]


def print_rtl(matrix, r):
    r.extend(matrix[-1][::-1])
    return matrix[:len(matrix)-1]


def print_btt(matrix, r):
    r.extend([row[0] for row in matrix[::-1]])
    return [row[1:] for row in matrix]


def sprial_print(matrix):
    direction = 0
    result = []
    while matrix:
        if direction == 0:
            matrix = print_ltr(matrix, result)
        if direction == 1:
            matrix = print_ttb(matrix, result)
        if direction == 2:
            matrix = print_rtl(matrix, result)
        if direction == 3:
            matrix = print_btt(matrix, result)
        direction = (direction + 1) % 4
    print(result)


matrix = [
    [1, 2, 3, 4, 5, 6, 7, 8],
    [9, 0, 1, 2, 3, 4, 5, 6],
    [7, 8, 9, 0, 1, 2, 3, 4],
    [5, 6, 7, 8, 9, 0, 1, 2]
]

sprial_print(matrix)
# [1, 2, 3, 4, 5, 6, 7, 8, 6, 4, 2, 1, 0, 9, 8, 7, 6, 5, 7, 9, 0, 1, 2, 3, 4, 5, 3, 2, 1, 0, 9, 8]