introductionToProgramming/week3/Gambler.java

public class Gambler {
  public static void main(String[] args) {
    // Run trials experiments that start with
    // $stake and terminate on $0 or $goal.
    int stake = Integer.parseInt(args[0]);
    int goal = Integer.parseInt(args[1]);
    int trials = Integer.parseInt(args[2]);
    double probability = Double.parseDouble(args[3]);
    int bets = 0;
    int wins = 0;
    for (int t = 0; t < trials; t++) {
      // Run one experiment.
      int cash = stake;
      while (cash > 0 && cash < goal) {
        // Simulate one bet.
        bets++;
        if (Math.random() < probability)
          cash++;
        else
          cash--;
      }
      // Cash is either 0 (ruin) or $goal (win).
      if (cash == goal)
        wins++;
    }
    System.out.println(100 * wins / trials + "% wins");
    System.out.println("Avg # bets: " + bets / trials);
  }
}