题解 | #判断两个IP是否属于同一子网#

def check_ip(ip):
    lst = ip.split('.')
    if len(lst) != 4:
        return False
    for i in lst:
        if not i.isdigit():
            return False
        if int(i) not in range(0, 256):
            return False
    return True

def check_mask(mask):
    lst = mask.split('.')
    if len(lst) != 4:
        return False
    bstr = ''
    for i in lst:
        if not i.isdigit():
            return False
        if int(i) not in range(0, 256):
            return False
        temp = bin(int(i)).replace('0b', '')
        bstr += (8-len(temp)) * '0' + temp
    if '0' not in bstr or '1' not in bstr or '01' in bstr:
        return False
    return True

def check_sub(ip1, ip2, mask):
    lst1, lst2, lst_mask = ip1.split('.'), ip2.split('.'), mask.split('.')
    for i in range(4):
        n1, n2, m = int(lst1[i]), int(lst2[i]), int(lst_mask[i])
        if n1 & m != n2 & m:
            return False
    return True

while True:
    try:
        mask, ip1, ip2 = input(), input(), input()
        if check_ip(ip1) and check_ip(ip2) and check_mask(mask):
            if check_sub(ip1, ip2, mask):
                print(0)
            else:
                print(2)
        else:
            print(1)
    except:
        break