【DFS + backtrack】LeetCode 93. Restore IP Addresses

LeetCode 93. Restore IP Addresses

Solution1：我的答案

怎么就这么慢。。。

class Solution {
public:
    vector<string> restoreIpAddresses(string s) {
        set<string> res;
        vector<string> temp;
        my_res(res, temp, s, 0);
        return vector<string>(res.begin(), res.end());
    }

    void my_res(set<string>& res, vector<string>& temp, string& s, int start) {
        if (temp.size() == 4 && start == s.size()) {
            res.insert(temp[0] + "." + temp[1] + "." + temp[2] + "." + temp[3]);
            return;
        } else if (temp.size() == 4 && start < s.size() 
                   || temp.size() < 4 && start == s.size())
            return;
        else {
            for (int i = start; i < s.size(); i++) {
                string temp_str = s.substr(start, i - start + 1);
                if (temp_str.size() == 1 || (temp_str.size() > 1 && temp_str[0] != '0') 
                    && atoi(temp_str.c_str()) >= 0 && atoi(temp_str.c_str()) <= 255) {
                    temp.push_back(temp_str);
                    my_res(res, temp, s, i + 1);
                    temp.pop_back();
                }
            }
        }
    }
};

C++中string和int转换

参考链接
https://www.cnblogs.com/smile233/p/8379802.html