Restore IP Addresses

Restore IP Addresses

 

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

For example:
Given25525511135,

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

Solution:

Main Idea: add one by one to the final ip address in recursive Mode

 

void formIpAddr(vector
 
  &ret, string curIp, string nums, int idxIp){        if(idxIp==1){            if(nums.size()>3 || (nums.size()>1&&nums[0]=='0')){                return ;            }            const char * data=nums.c_str();            if(nums.size()<=2||atoi(data)<=255){                ret.push_back(curIp+nums);                return;            }        }        else{            if(nums[0]=='0'){                string tmp=curIp+nums.substr(0,1)+.;                formIpAddr(ret, tmp, nums.substr(1), idxIp-1);                return;            }            else{                int i;                string tmp;                for(i=0; i<2 && i+idxIp<=nums.size(); i++){                    tmp=nums.substr(0, i+1);                    formIpAddr(ret, curIp+tmp+., nums.substr(i+1), idxIp-1);                }                if(i+idxIp<=nums.size()){                    const char * data=nums.substr(0,i+1).c_str();                    tmp=nums.substr(0, i+1);                    if(atoi(data)<=255)                        formIpAddr(ret, curIp+tmp+., nums.substr(i+1), idxIp-1);                }            }        }            }    vector
  
    restoreIpAddresses(string s) {        vector
   
     ret;        if(s.size()<4)            return ret;        string curIp=;                formIpAddr(ret, curIp, s, 4);        return ret;    }