题解 | IP地址

#include<bits/stdc++.h>
using namespace std;
bool func1(string str){
    if(str[0] == '0' && str.size() > 1){
        return false;
    }
    return true;
}
bool judge(string str){
    vector<string> address;
    int len = str.size();
    int beginpos = 0;
    for(int i = 0; i <= len; i++){
        if(str[i] == '.' || i == len){
            address.push_back(str.substr(beginpos, i - beginpos));
            beginpos = i + 1;
        }
    }
    if(address.size() != 4){
        return false;
    }
    for(int i = 0; i < 4; i++){
        if(!func1(address[i])){
            return false;
        }
    }
    for(int i = 0; i < 4; i++){
        if(stoi(address[i]) < 0 || stoi(address[i]) > 255){
            return false;
        }
    }
    return true;
}
int main(){
    string str;
    while(cin >> str){
        if(judge(str)){
            cout << "Yes!" << endl;
        }
        else{
            cout << "No!" << endl;
        }
    }
    return 0;
}

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