题解 | #识别有效的IP地址和掩码并进行分类统计#

#include <iostream>
#include <sstream>
#include <string>
#include <vector>
#include <cstring>
using namespace std;

int main() {
    vector<string> a;
    string str;
    int len = 0;
    int A = 0,B = 0,C = 0, D = 0, E = 0, er = 0, pri = 0;
    while(getline(cin,str))
    {
        if(str!="")
        {
            a.push_back(str);
            len++;
        }
        
    }
    for(int i = 0; i < len; i++)
    {
        stringstream ss;
        ss<<a[i];//一行输入
        vector<string> s;//存储一行中的IP和子网掩码;s[0]-ip;s[1]-子网掩码
        vector<string> ip;//存储ip4个字段；
        vector<string> subnet;//存储子网掩码四个字段 
        string temp;
        while (getline(ss,temp,'~'))//用~隔开 
        {
            s.push_back(temp);
        }
        stringstream ss1,ss2;
        ss1<<s[0];
        ss2<<s[1];
        string temp1,temp2;
        while(getline(ss1,temp1,'.'))
        {
            ip.push_back(temp1);
        }
        while(getline(ss2,temp2,'.'))
        {
            subnet.push_back(temp2);
        }
        //ip或者掩码字段长度有误
        if(ip.size()!=4||subnet.size()!=4)
        {
            er ++; 
            continue;
        }
        //判断是否为0或者127开头
        if(ip[0].size() == 1&&ip[0] == "0")
        {
            continue;
        }
        if(ip[0].size()==3&&ip[0]=="127")
        {
            continue;
        }
        //判断ip和子网掩码是否合法
        bool error = true;
        vector<int> subnetInt(32,0);//将子网掩码转换为二进制
        for(int j = 0; j < 4; j++)
        {
            int num = 0;
            if(ip[j] == "")
            {
                error = false;
                break;
            }
            if(ip[j].size() > 3)
            {
                error = false;
                break;
            }
            if(ip[j].size() == 3)
            {
                num = (ip[j][0]-48)*100+(ip[j][1]-48)*10+ip[j][2]-48;
                if(num>255)
                {
                    error = false;
                    break;
                }
            }
            int tempInt = 0;
            if(subnet[j].size()==3)
            {
                tempInt = (subnet[j][0]-48)*100+(subnet[j][1]-48)*10+subnet[j][2]-48;
            }
            if(subnet[j].size()==2)
            {
                tempInt = (subnet[j][0]-48)*10+subnet[j][1]-48;
            }
            if(subnet[j].size()==1)
            {
                tempInt = subnet[j][0]-48;
            }
            int count = (j+1)*8 -1 ;
            if(tempInt != 0)
            {   
                int tem = tempInt;
                while(tem/2!=0)//转为二进制
                {
                    int n = tem%2;
                    subnetInt[count] = n;
                    count--;
                    tem/=2;
                }
                subnetInt[count] = 1;
            }
            // for(auto i:subnet)
            //     cout<<i<<" ";
            int flag = 1;
            int numOf1 = 0;
            int rflag = 1;
            int numOf0 = 0;
            for(int t = 0; t <32; t++)
            {
                if(subnetInt[t]==1&&flag == 1)
                {
                    numOf1 ++;
                }
                if(subnetInt[t] == 0)
                {
                    flag = 0;
                    break;
                }
            }
            for(int t = 31; t >=0; t--)
            {
                if(subnetInt[t]==0&&rflag == 1)
                {
                    numOf0 ++;
                }
                if(subnetInt[t] == 1)
                {
                    rflag = 0;
                    break;
                }
            }
            if(numOf0==32||numOf1==32||numOf0+numOf1!=32)
            {
                error = false;
            }  
        }
        if(!error)
        {
            er++;
            continue;
        }
        int ipInt = 0;
        int ipInt2 = 0;
        if(ip[0].size() == 1)
        {
            ipInt = ip[0][0]-48;
        }
        if(ip[0].size() == 2)
        {
            ipInt = (ip[0][0]-48)*10+ip[0][1]-48;;
        }
        if(ip[0].size() == 3)
        {
            ipInt = (ip[0][0]-48)*100+(ip[0][1]-48)*10+ip[0][2]-48;;
        }
        if(ip[1].size() == 1)
        {
            ipInt2 = ip[1][0]-48;
        }
        if(ip[1].size() == 2)
        {
            ipInt2 = (ip[1][0]-48)*10+ip[1][1]-48;;
        }
        if(ip[1].size() == 3)
        {
            ipInt2 = (ip[1][0]-48)*100+(ip[1][1]-48)*10+ip[1][2]-48;;
        }
        if(ipInt<127)
            A++;
        if(ipInt>127&&ipInt<192)
            B++;
        if(ipInt>191&&ipInt<224)
            C++;
        if(ipInt>223&&ipInt<240)
            D++;
        if(ipInt>239)
            E++;
        if(ipInt == 10)
            pri++;
        if(ipInt == 172&&ipInt2>15&&ipInt2<32)
            pri++;
        if(ipInt == 192&&ipInt2==168)
            pri++;
    }
    cout<<A<<" "<<B<<" "<<C<<" "<<D<<" "<<E<<" "<<er<<" "<<pri;
    
    
    
}
// 64 位输出请用 printf("%lld")