题解 | 判断两个IP是否属于同一子网

#include <algorithm>
#include <iostream>
#include <istream>
#include <sstream>
#include <vector>
using namespace std;

string toBinary(int n)
{
    string binary;
    while(n != 0)
    {
        binary = n%2 ? '1' + binary : '0' + binary;
        n = n/2;
    }

    string zero(8 - binary.size(), '0');
    return  zero + binary;
}

bool youxiaoip(string& ip, string &binaryip) {
    istringstream iss(ip + '.');
    string str;
    while (getline(iss, str, '.')) {
        istringstream isss(str);
        int n;
        isss >> n;
        if (n < 0 || n > 255) {
            return false;
        }

        binaryip += toBinary(n);
    }

    return true;
}

bool youxiaoyanma(string& yanma, string &binaryyanma) {
    istringstream iss(yanma + '.');
    string str;
    while (getline(iss, str, '.')) {
        istringstream isss(str);
        int n;
        isss >> n;
        if (n < 0 || n > 255) {
            return false;
        }

        binaryyanma += toBinary(n);
    }

    auto it = binaryyanma.find_first_of('0');
    if(it != string::npos)
    {
        string zero = binaryyanma.substr(it);
        if(count(zero.begin(), zero.end(), '0') != zero.size())
        {
            return false;
        }
    }

    return true;
}

string yuyunsuan(string &ip, string &yanma)
{
    string res;
    for(int i = 0; i < ip.size(); i++)
    {
        if(ip[i] == '0' || yanma[i] == '0')
        {
            res += '0';
        }
        else{
            res += '1';
        }
    }

    return res;
}

int main() {
    string yanma, ip1, ip2;
    while (getline(cin, yanma)) {
        getline(cin, ip1);
        getline(cin, ip2);

        string binaryip1, binaryip2, binaryyanma;
        if(youxiaoyanma(yanma, binaryyanma) &&
             youxiaoip(ip1, binaryip1) &&
             youxiaoip(ip2, binaryip2))
             {
                    if(yuyunsuan(binaryip1, binaryyanma) == 
                        yuyunsuan(binaryip2, binaryyanma))
                        {
                            cout<<0<<endl;
                        }
                        else{
                            cout<<2<<endl;
                        }
             }
        else{
            cout<<1<<endl;
        }
    }
}
// 64 位输出请用 printf("%lld")