topcoder SRM 593 DIV2 WolfDelaymaster

 #include <iostream>
 #include <string>
 #include <algorithm>

 using namespace std;

 class WolfDelaymaster{
 public:
     bool checkChar(string str, char c, int start ,int num){
         for(int i = start; i < start + num; ++ i ){
             if(str[i] != c) return false;
         }
         return true;
     }

     string check(string str){
         for(int i = ; i < str.length();){
             int j = i;
             while(str[j] == 'w' && ++ j);
             int num = j - i;
             if(num ==  ) return "INVALID";
             if(checkChar(str,'',j,num) && checkChar(str,'l',j+num,num) && checkChar(str,'f',j+*num,num))
             {
                 i = j + *num;
             }
             else return "INVALID";
         }
         return "VALID";
     }

 };