Python,codewars,The observed PIN

'''
The observed PIN,https://www.codewars.com/kata/5263c6999e0f40dee200059d/train/python
'''
def get_pins(observed):
    adjacent = {
        '0' : '08',              # 0
        '1' : '124',          # 1
        '2' : '1235',      # 2
        '3' : '236',          # 3
        '4' : '1457',      # 4
        '5' : '24568',  # 5
        '6' : '3569',      # 6
        '7' : '478',          # 7
        '8' : '57890',  # 8
        '9' : '689'           # 9
    }
    result = ['']
    for ch in observed:
        result = [x+y for x in result for y in adjacent[ch]]
    return result

# other's solution learning

from itertools import product

ADJACENTS = ('08', '124', '2135', '326', '4157', '52468', '6359', '748', '85790', '968')

def get_pins_other(observed):
    # *运算符用于解包一个可迭代独享, 在函数调用中使用*运算符时, 会将可迭代对象中的元素作为单独的参数传递给函数
    # product()函数用于求多个可迭代对象的笛卡尔积,笛卡尔积是一个集合,其中每个元素是一个元组,
    # 元组的第一个元素取自第一个输入的可迭代对象,第二个元素取自第二个输入的可迭代对象,以此类推
    # 例如: product('ABCD', 'xy') --> Ax Ay Bx By Cx Cy Dx Dy
    # join()方法用于将序列中的元素以指定的字符连接生成一个新的字符串
    return [''.join(p) for p in product( *(ADJACENTS[int(d)] for d in observed) )]