resotreIpAddress

Given a string containing only digits, restore it by returning all possible valid IP address combinations.

For example:
Given "25525511135",

return ["255.255.11.135", "255.255.111.35"]. (Order does not matter)

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 #include <string>
 #include <vector>
 using namespace std;
 class Solution {
 public:
     vector<string> restoreIpAddresses(string s) {
         vector<string> result;
         vector<int> path;
         dfs(s,,,path,result);
         return result;
     }
 private:
     void dfs(string& s,int start,int num,
         vector<int>& path,vector<string>& result){
         if(num == ) {
             string str = s;
             for(int i=;i<;i++){
                 str.insert(path[i]+i,,'.');
             }
             result.push_back(str);
             return;
         }

         for(int i=;i<;i++){
             if((start+i)<s.length() && -num<=s.substr(start+i).length() && s.substr(start+i).length()<=(-num)*){
                 if(stoi(s.substr(start,i))<=){
                     if(i> && s[start] =='') break;
                     if(num== && stoi(s.substr(start+i))>) continue;
                     if(num== && s.substr(start+i).length()> && s[start+i]=='') continue;

                     if(path.empty()) path.push_back(i);
                     else path.push_back(path.back()+i);
                      dfs(s,start+i,num+,path,result);
                      path.pop_back();
                 }
             }
         }
     }
 };
 int main(){
     string IPaddress="";
     Solution s;
     vector<string> result;
     result = s.restoreIpAddresses(IPaddress);
     return ;
 }