code/HongRuan/question3.cpp

/*
验证ipv4是否合法

*/
#include <bits/stdc++.h>
using namespace std;

vector<string> split(string s, string spliter) {
    vector<string> res;
    int i;
    //遍历字符串查找spliter
    while ((i = s.find(spliter)) && i != s.npos) {
        //将分割的部分加入vector中
        res.push_back(s.substr(0, i));
        s = s.substr(i + 1);
    }
    res.push_back(s);
    return res;
}
bool isIPv4(string IP) {
    vector<string> s = split(IP, ".");
    if (s.size() != 4)
        return false;
    for (int i = 0; i < s.size(); i++) {
        //不可缺省，有一个分割为零，说明两个点相连
        if (s[i].size() == 0)
            return false;
        //比较数字位数及不为零时不能有前缀零
        if (s[i].size() < 0 || s[i].size() > 3 || (s[i][0] == '0' && s[i].size() != 1))
            return false;
        //遍历每个分割字符串，必须为数字
        for (int j = 0; j < s[i].size(); j++)
            if (!isdigit(s[i][j]))
                return false;
        //转化为数字比较，0-255之间
        int num = stoi(s[i]);
        if (num < 0 || num > 255)
            return false;
    }
    return true;
}

int solve(string IP) {
    // write code here
    if (IP.size() == 0)
        return 0;
    if (isIPv4(IP))
        return 1;
    return 0;
}
int main() {
    string str;
    cin >> str;
    cout << solve(str) << endl;
    return 0;
}