原题传送门

1. 题目描述

2. Solution

1、思路
把ip全转换为32bit 字符串，模拟与运算。
2、实现

import sys

if sys.platform != "linux":
    file_in = open("input/HJ39.txt")
    sys.stdin = file_in

"""
若IP地址或子网掩码格式非法则输出1，若IP1与IP2属于同一子网络输出0，若IP1与IP2不属于同一子网络输出2。
"""


def is_valid_ip(s):
    if ".." in s:
        return False
    for x in list(map(int, s.split("."))):
        if x < 0 or x > 255:
            return False
    return True


def is_valid_mask(mask):
    if not is_valid_ip(mask):
        return False
    mask_bin = ip2bin(mask)
    if '0' not in mask_bin or '1' not in mask_bin or '01' in mask_bin:
        return False
    return True


def int2bin(n):
    n_bin = bin(n).replace("0b", "")
    return f'{"0" * (8 - len(n_bin))}{n_bin}'


def ip2bin(s):
    nums = list(map(int, s.split(".")))
    return "".join([int2bin(x) for x in nums])


def solve(ip1, ip2, mask):
    if not is_valid_ip(ip1) or not is_valid_ip(ip2) or not is_valid_mask(mask):
        print(1)
        return
    ip1_bin = ip2bin(ip1)
    ip2_bin = ip2bin(ip2)
    mask_bin = ip2bin(mask)
    for i in range(32):
        if mask_bin[i] == '0':
            continue
        if ip1_bin[i] != ip2_bin[i]:
            print(2)
            return
    print(0)


while True:
    try:
        mask = input().strip()
        ip1 = input().strip()
        ip2 = input().strip()
        solve(ip1, ip2, mask)
    except:
        break

标签：bin,return,mask,ip2,牛客,HJ39,ip1,机试,valid
来源： https://www.cnblogs.com/junstat/p/16168268.html