题解 | #验证IP地址#

#include <cstdlib>
#include <iterator>
class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 验证IP地址
     * @param IP string字符串 一个IP地址字符串
     * @return string字符串
     */

    vector<string> Split(string IP)
    {
        vector<string> temp;
        string block = "";
        for(int i = 0;i<IP.size();i++)
        {
            if(IP[i] != '.' && IP[i] != ':')
            {
                block += IP[i];
                if(i == IP.size() - 1)
                {
                    temp.push_back(block);
                    break;
                }
            }
            else
            {
                temp.push_back(block);
                block = "";
                if(i == IP.size()-1) temp.push_back(block);//这一行写的很差，为了过测试点的
            }
        }
        return temp;
    }

    bool isIPv4(string IP)
    {
        int index = IP.find('.');
        if(index != string::npos) return true;
        else return false;
    }

    bool checkIPv4(string str)
    {
        if(str.size() > 3) return false;
        if(str == "") return false;
        for(int i = 0;i<str.size();i++)
        {
            if(str[i] < '0' || str[i] > '9') return false;
        }
        int value = atoi(str.c_str());
        if(value > 255) return false;
        char first = str[0];
        if(first == '0' && str.size() != 1) return false;
        return true;
    }

    bool checkIPv6(string str)
    {
        if (str.size() > 4 || str.size() == 0)
        {
            return false;
        }
        for (int i = 0; i < str.size(); i++)
        {
            if (!(isdigit(str[i]) || (str[i] >= 'a' && str[i] <= 'f') || (str[i] >= 'A' && str[i] <= 'F')))
            {
                return false;
            }

        }
        return true;
    }

    string solve(string IP) {
        // write code here
        vector<string> ss;
        ss = Split(IP);
        if(isIPv4(IP))
        {
            if(ss.size() != 4) return "Neither";
            for(int i = 0;i<ss.size();i++)
            {
                if(!checkIPv4(ss[i])) return "Neither";
            }
            return "IPv4";
        }
        else
        {
            if(ss.size() != 8) return "Neither";
            for(int i = 0;i<ss.size();i++)
            {
                if(!checkIPv6(ss[i])) return "Neither";
            }
            return "IPv6";
        }
    }
};