题解 | #判断两个IP是否属于同一子网#

def check_ip(ip):
    ip_s = ip.split('.')
    if len(ip_s) != 4:
        return False
    else:
        for i in ip_s:
            if int(i) < 0 or int(i) > 255:
                return False

    return True


def check_mask(mask):
    if not check_ip(mask):
        return False
    elif mask in ["255.255.255.255.255", "0.0.0.0"]:  # 不用判断吗 我看咋都不判断
        return False
    else:
        mask_s = mask.split('.')
        temp_bin = "".join([bin(int(i))[2:].rjust(8,'0') for i in mask_s])
        index = temp_bin.index('0')
        # if temp_bin[index:].count('1') > 0:
        #     return False
        if temp_bin.find('01') != -1:
            return False

    return True

while True:
    try:
        mask,ip1,ip2 = input(),input(),input()

        out = 1
        if not check_mask(mask) or not check_ip(ip1) or not check_ip(ip2):
            out = 1
        else:
            num_mask = list(map(int,mask.split('.')))
            num_ip1 =  list(map(int,ip1.split('.')))
            num_ip2 =  list(map(int,ip2.split('.')))
            res1 = [num_mask[i] & num_ip1[i] for i in range(4)]
            res2 = [num_mask[i] & num_ip2[i] for i in range(4)]
            out = 0 if res1 == res2 else 2


        print(out)
    except:
        break