题解 | #验证IP地址#

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
     */
    string solve(string IP) {
        // write code here
        if (is_ipv4(IP)) {
            return "IPv4";
        }
        if (is_ipv6(IP)) {
            return "IPv6";
        }
        return "Neither";
    }
private:
    bool is_ipv4(const std::string& ip) {
        auto res = split(ip, '.');
        if (res.size() != 4) {
            return false;
        }
        for (int i = 0; i < res.size(); i++) {
            if (res[i].empty()) {
                return false;
            }
            if (res[i][0] == '0') {
                return false;
            }
            for (int k = 0; k < res[i].size(); k++) {
                if (!isdigit(res[i][k])) {
                    return false;
                }
            }
            if (stoi(res[i]) > 255 || stoi(res[i]) < 0) {
                return false;
            }
        }
        return true;
    }
private:
    bool is_ipv6(const std::string& ip) {
        auto res = split(ip, ':');
        if (res.size() != 8) {
            return false;
        }
        for (int i = 0; i < res.size(); i++) {
            if (res[i].empty()) {
                return false;
            }
            if (res[i].size() > 4) {
                return false;
            }
            for (int k = 0; k < res[i].size(); k++) {
                if (isdigit(res[i][k]) || res[i][k] >= 'a' && res[i][k] <= 'f' || (res[i][k] >= 'A' && res[i][k] <= 'F')) {
                    continue;
                } else {
                    return false;
                }
            }
        }
        return true;
    }
private:
    std::vector<std::string> split(const string& str, char delim) {
        std::vector<std::string> res;
        std::string tmp;
        for (int i = 0; i < str.size(); i++) {
            if (str[i] != delim) {
                tmp.push_back(str[i]);
            } else {
                res.push_back(tmp);
                tmp.clear();
            }
        }
        res.push_back(tmp);

        return res;
    }
};