leetcode93 Restore IP Addresses

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) {
        vector<string> ans;
        vector<int> cur(8,0);
        dep(ans,s,0,cur,0);
        return ans;
    }
    
    void dep(vector<string> &ans,string s,int ps,vector<int>&cur,int pc)
    {
        int len=s.length();
        for(int i=1;i<=3;i++)
        {
            if(ps+i<=len)
            {
                if(judge(s.substr(ps,i)))
                {
                    cur[pc]=ps;
                    cur[pc+1]=i;
                    if(ps+i==len&&pc==6)
                        addstr(ans,s,cur);
                    else if(ps+i!=len&&pc!=6)
                        dep(ans,s,ps+i,cur,pc+2);
                }
            }
        }
    }
    
    bool judge(string str)
    {
        if(str.length()>1&&str[0]=='0')
            return false;
        int temp=atoi(str.c_str());
        if(temp>=0&&temp<=255)
            return true;
        return false;
    }
    
    void addstr(vector<string> &ans,string s,vector<int>&cur)
    {
        string temp="";
        temp+=s.substr(cur[0],cur[1]);
        temp+=".";
        temp+=s.substr(cur[2],cur[3]);
        temp+=".";
        temp+=s.substr(cur[4],cur[5]);
        temp+=".";
        temp+=s.substr(cur[6],cur[7]);
        ans.push_back(temp);
    }
};