BFS-ShortestPath.cpp

bool isChild(string str1, string str2)
{
    if(str1.length() != str2.length())
    return false;
    
    int i = 0;
    int count = 0;
    while(i < str1.length())
    {
        if(str1[i] != str2[i])
        {
            count++;
        }
    }
    
    return count == 1 ? true : false;
    
}

int Solution::ladderLength(string start, string end, vector<string> &dictV) {
    
   std::deque<string> q;
   q.push_back(start);
   std::set<string> s;
    s.insert(start);
   int counter = 0;
   bool found = false;
   
   if(start.length() != end.length()) return 0;

   while(!q.empty())
   {
       string str = q.front();
       q.pop_front();
      
       if(str == end)
       {
           found = true;
           break;
       }
       
       for(int i = 0; i < dictV.size(); i++)
       {
           if(s.find(dictV[i]) == s.end() && isChild(str,dictV[i]))
           {
                q.push_back(dictV[i]);
                s.insert(dictV[i]);
           }
       }
       
       counter++;
   }
    
   if(found)
   {
       return counter;
   }
   else
   {
       return 0;
   }
}