public class CoinFlipHistogram {

  public static void main (String[] argv)
  {
    try {
      if ( (argv == null) || (argv.length != 2) ) {
        System.out.println ("Usage: CoinFlipHistogram <numFlips> <numTrials>");
        System.exit(1);
      }

      int numFlips = Integer.parseInt (argv[0]);
      int numTrials = Integer.parseInt (argv[1]);

      computeHistogram (numFlips, numTrials);
    }
    catch (Exception e) {
      e.printStackTrace();
    }
  }
  
  static void computeHistogram (int numFlips, int numTrials)
  {
    // Create space for the bins.
    int[] bins = new int [numFlips+1];


    // Perform trials.

    for (int i=0; i<numTrials; i++) {

      // Flip coins "numFlips" times and count.
      int count = 0;
      for (int j=0; j<numFlips; j++) {
        if (UniformRandom.uniform() < 0.5) {
          // Heads.
          count ++;
        }
      }

      // Update counter.
      bins[count] ++;
    }

    System.out.println ("Histogram: ");
    System.out.println ("  Bin   #Trials   Fraction");
    for (int i=0; i<=numFlips; i++) {
      System.out.println ("  " + i + "      " + bins[i] + "        " 
                          + ((double)bins[i]/(double)numTrials) );
    }
  }

}