leetcode 125: Restore IP Addresses (uncompleted)

Restore IP Addresses Aug 8 '12

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)

 

 

class Solution {
public:
    vector<string> restoreIpAddresses(string s) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
     //  Given "25525511135",
       // ["255.255.11.135", "255.255.111.35"]
    
        vector<string> res;
        string temp;
        
        ipRec(res, temp, s, 0, 0);
        return res;
    }
    
private:
    void ipRec(vector<string>& res, string& temp, string& s, int level, int index) {
        if(level==4) {
            if(index==s.length()) {
                temp.pop_back();
                res.push_back(temp);
            }
            return;
        }
        
        string t;
        
        for(int i=0; i<3; i++) {
            t.push_back(s[index+i]);
            if(!isValid(t)) continue;
            
            temp.append(t);
            temp.push_back('.');
            ipRec(res, temp, s, level+1, index+i+1);
            temp.pop_back();
        }
    }

    bool isValid(string s) {
        if(s.length()<1 || s.length()>3) return false;
        
        if(s.length()==3 && s[2]==0) return false;
        if(s.length()==2 && s[1]==0) return false;
        
        int x=atoi(s.c_str());
        
        if( x>=0 && x<=255) return true;
        else return false;
    }
};