题解 | #识别有效的IP地址和掩码并进行分类统计#

xdm 注意这句话 ！！！！！！！ 只能过80%，试了几个小时

类似于【0...】和【127...】的IP地址不属于上述输入的任意一类，也不属于不合法ip地址，计数时请忽略

#include<sstream>
using namespace std;
bool Analysis(string& address, vector<int>& res)
{
    int start = 0;
    stringstream s;
    int d1 = address.find('.');
    int d2 = address.find('.',d1 + 1);
    int d3 = address.find('.',d2 + 1);
    vector<string>strs(4);
    strs[0] = address.substr(0,d1);
    strs[1] = address.substr(d1 + 1,d2 - d1 - 1);
    strs[2] = address.substr(d2 + 1,d3 - d2 - 1);
    strs[3] = address.substr(d3 + 1);
    for(auto str : strs)
    {
        if(str.size() == 0)return false;
    }
    for(int i = 0;i < 4;i++)
    {
        int num;
        s.clear();
        s << strs[i];
        s >> num;
        if(num < 0 || num > 255)return false;
        res[i] = num;
    }
    return true;
}
bool isValid(vector<int> vec)
{
    if(vec[0] == 0 && vec[1] == 0 && vec[2] == 0 && vec[3] == 0)return false;
    if(vec[0] == 255 && vec[1] == 255 && vec[2] == 255 && vec[3] == 255)return false;
    int flag = 1;
    for(int i = 0;i < 4;i++)
    {
        int tmp = vec[i];
        if(flag == 1 && tmp < 255)
        {
            if(tmp != 254 && tmp != 252 && tmp != 248 && tmp != 240 && tmp != 224 && tmp != 192 && tmp != 128 && tmp != 0)
            {
                return false;
            }
            flag = 0;
        }
        else if(flag == 0 && tmp != 0)
        {
            return false;
        }
    }
    return true;
}
int main()
{
    string str;
    int A,B,C,D,E,errors,private_ip;
    A = B = C = D = E = errors = private_ip = 0;
    while(cin >> str)
    {
        int pos = str.find('~');
        string ip = str.substr(0,pos);
        string code = str.substr(pos + 1);
        //解析ip和子网掩码
        vector<int> Ip(4); 
        vector<int> Code(4); 
        //判断地址是否合法
        if((!Analysis(ip, Ip)) || (!Analysis(code,Code)) || (!isValid(Code)))
        {
            if(Ip[0] == 0 || Ip[0] == 127)continue;
            errors++;
        }
        else
        {
                    //首先判断ABCDE
        if(Ip[0] >= 1 && Ip[0] <= 126)A++;
        if(Ip[0] >= 128 && Ip[0] <= 191)B++;
        if(Ip[0] >= 192 && Ip[0] <= 223)C++;
        if(Ip[0] >= 224 && Ip[0] <= 239)D++;
        if(Ip[0] >= 240 && Ip[0] <= 255)E++;
        //再判断是否为私网ip
        if((Ip[0] == 10) || (Ip[0] == 172 && (Ip[1] >= 16 && Ip[1] <= 31)) || (Ip[0] == 192 && Ip[1] == 168))
        {
            private_ip++;
        }
        }
    }
    cout << A << " " << B << " " << C << " " << D << " " << E << " " << errors << " " << private_ip;
    return 0;
}