2013 SWERC D

One exercise about Full Metal Alchemist!

#include<iostream>
#include<string>
#include<vector>

using namespace std;

string hall(string);

int main(){
 int nn;
 cin>>nn;
 for(int z=0;z<nn;z++){
  int n;
  cin>>n;
  string s;
  cin>>s;
  
  string t="";
  for (int i=0;i<n;i++){
   t=hall(t);
  }
  
  cout<< ((t.find(s)==string::npos)?"no":"yes")<<endl;
 }
}

string hall(string s){
 if(s=="") return string("L");
 string res="L";
 char toca='R';
 for(int i=0;i<s.size();i++){
  res+=s[i]+string("")+toca;
  toca=(toca=='L'?'R':'L');
 }
 return res;
}