import sraja.lib.java.*;
import java.util.*;

// a pair of counters to keep track of the number of heads and tails
// following a sequence of 4 guesses


public class Memory {

  // an inner class
  class HTcounter {
    int nHead=0, nTail=0;
    
    public String toString () {
      return "[H: " + nHead + " T: " + nTail + "]";
    }
  }

  private Hashtable store = new Hashtable ();

  char retrieve (ShiftBuffer sb) {
    String key = sb.toString();
    if (store.containsKey (key)) {
      HTcounter htc = (HTcounter) store.get(key);
      return (htc.nHead > htc.nTail ? 'h' : 't');
    } else {
      return
        (Math.random() > 0.5) ? 'h' : 't' ;
    }
  }

  void store (ShiftBuffer sb, char guess) {
    HTcounter htc;
    String key = sb.toString();
    if (store.containsKey (key)) {
      htc = (HTcounter) store.get(key);
    } else { // make a new pair of counters and store them in memory
      htc = new HTcounter ();
      store.put(key,htc);
    }
    if (guess == 'h') 
      htc.nHead++;
    else
      htc.nTail++;
  }
  
  public String toString () {
    return "Memory:\n" + store;
  }

// for testing

  public static void main (String[] args) {
    Memory mem = new Memory ();
    Stdio.println (mem.toString());
    ShiftBuffer sb = new ShiftBuffer (4);
    mem.store(sb,'h');
    sb.shift('t');
    mem.store(sb,'h');
    mem.store(sb,'h');
    System.out.println (mem);
  }
}