【慕课网】如何快速找到多个字典中的公共键

# '西班牙足球甲级联赛，每轮球员进球统计：
# 第一轮：{'苏亚雷斯':1,'梅西':2,'本泽马':1,'c罗':3}
# 第二轮：{'苏亚雷斯':1,'c罗':1,'格里兹曼':2,'贝尔':1}
# 第三轮：{'苏亚雷斯':1,'托雷斯':2,'贝尔':1,'内马尔':3}
# .....
# 统计出前N轮，每场比赛都有进球的球员
from functools import reduce
from random import randint, sample


def main():
    # sample随机取样
    # a=sample ('abcdefg',3)
    a = sample('abcdefg', randint(3, 6))

    s1 = {x: randint(1, 4) for x in sample('abcdefg', randint(3, 6))}
    s2 = {x: randint(1, 4) for x in sample('abcdefg', randint(3, 6))}
    s3 = {x: randint(1, 4) for x in sample('abcdefg', randint(3, 6))}
    # print(s1,s2,s3)
    res = []
    for k in s1:
        if k in s2 and k in s3:
            res.append(k)
    print(res)
    pass


def main2():
    # sample随机取样
    # a=sample ('abcdefg',3)
    a = sample('abcdefg', randint(3, 6))

    s1 = {x: randint(1, 4) for x in sample('abcdefg', randint(3, 6))}
    s2 = {x: randint(1, 4) for x in sample('abcdefg', randint(3, 6))}
    s3 = {x: randint(1, 4) for x in sample('abcdefg', randint(3, 6))}
    # print(s1,s2,s3)
    # 利用集合（set的交集）
    # 1 使用字典的viewkeys()方法 得到字典keys的集合
    # 2 使用map函数，得到所有字典的keys的集合
    # 3 使用reduce函数，取所有字典的keys集合的交集
    print(s1.keys())
    print(s2.keys())
    print(s3.keys())
    # 取交集
    print(s1.keys() & s2.keys() & s3.keys())
    pass


def main3():
    # sample随机取样
    # a=sample ('abcdefg',3)
    a = sample('abcdefg', randint(3, 6))
    s1 = {x: randint(1, 4) for x in sample('abcdefg', randint(3, 6))}
    s2 = {x: randint(1, 4) for x in sample('abcdefg', randint(3, 6))}
    s3 = {x: randint(1, 4) for x in sample('abcdefg', randint(3, 6))}
    s5 = reduce(lambda a, b: a & b, map(dict.keys, [s1, s2, s3]))
    print(s5)
    pass


main3()