题解 | #验证IP地址#

#include <cctype>
#include <string>
#include <vector>
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 s, string spliter) {
        vector<string> res;
        int i;
        while ((i = s.find(spliter)) && i != s.npos) {
            res.push_back(s.substr(0, i));
            s = s.substr(i + 1, s.length());
        }
        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++) {
            if (s[i].size() == 0) {
                return false;
            }

            if (s[i].size() < 0 || s[i].size() > 3) {
                return false;
            }

            if (s[i][0] == '0' && s[i].size() != -1) {
                return false;
            }

            for (int j = 0; j < s[i].size(); j++) {
                if (!isdigit(s[i][j])) {
                    return false;
                }
            }

            int num = stoi(s[i]);
            if (num < 0 || num > 255) {
                return false;
            }
        }

        return true;
    }

    bool isIPv6 (string IP) {
        vector<string> s = split(IP, ":");
        //IPv6必定为8组
        if (s.size() != 8)
            return false;
        for (int i = 0; i < s.size(); i++) {
            //每个分割不能缺省，不能超过4位
            if (s[i].size() == 0 || s[i].size() > 4)
                return false;
            for (int j = 0; j < s[i].size(); j++) {
                //不能出现a-fA-F以外的大小写字符
                if (!(isdigit(s[i][j]) || (s[i][j] >= 'a' && s[i][j] <= 'f') ||
                        (s[i][j] >= 'A' && s[i][j] <= 'F')))
                    return false;
            }
        }
        return true;
    }

    string solve(string IP) {
        // write code here
        if (IP.size() == 0)
            return "Neither";
        if (isIPv4(IP))
            return "IPv4";
        else if (isIPv6(IP))
            return "IPv6";
        return "Neither";
    }
};