每日一题-LeetCode468-验证IP地址-字符串-模拟

原题链接

class Solution {
public:

    bool checkv4(string ip){
        if(ip.size() > 15)  return false;
        int num = 0;
        for(int i = 0, j = 0; i < ip.size();){
            string word = "";
            if(j < ip.size() && ip[j] == '.') j ++;
            while(j < ip.size() && ip[j] != '.') word += ip[j ++];
            if(word.size() == 0 || word.size() > 4 || (word.size() > 1 && word[0] == '0') ) return false;
            for(auto c: word){
                if(c >= '0' && c <= '9')    continue;
                else    return false;
            }
            if(stoi(word) >= 256)   return false;
            i = j;
            if(ip[i] == '.')    num ++;
        }
        if(num != 3) return false;
        return true;
    }

    bool checkv6(string ip){
        if(ip.size() > 39)  return false;
        int num = 0;
        for(int i = 0, j = 0; i < ip.size();){
            string word = "";
            if(j < ip.size() && ip[j] == ':')    j ++;
            while(j < ip.size() && ip[j] != ':')    word += ip[j ++];
            if(word.size() == 0 || word.size() > 4) return false;
            for(auto c: word){
                if((c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F'))    continue;
                else    return false;
            }
            i = j;
            if(ip[i] == ':')    num ++;
        }
        if(num != 7) return false;
        return true;
    }

    string validIPAddress(string queryIP) {
        if(checkv4(queryIP))    return "IPv4";
        if(checkv6(queryIP))    return "IPv6";
        return "Neither";
    }
};