Monty Hall Game Show Problem in Javascript

[kirupa]

And here is the code so simulate the Monty Hall problem for an arbitrary number of doors:

function montyHallSimulation(doorNum, runs) {
  // Track the results
  var wins = 0;
  var losses = 0;

  // Simulate the game
  for (var i = 0; i < runs; i++) {
    // Initialize the doors
    var doors = new Array(doorNum);
    doors.fill("x");

    let chosenDoor = Math.floor(Math.random() * doors.length);
    let carDoor = Math.floor(Math.random() * doors.length);
    let montyDoor = -1;

    doors[chosenDoor] = "chosen";
    doors[carDoor] = "car";

    // The player guessed correctly with their first pick!
    if (chosenDoor === carDoor) {
      doors[chosenDoor] = "chosen + car";

      // We need to reveal some arbitrary door that isn't the 
      // same one the player has selected
      do {
        montyDoor = Math.floor(Math.random() * doors.length);
        //console.log(`${montyDoor} is Monty's pick, and chosen is ${chosenDoor}`);
      } while (montyDoor == chosenDoor);

      doors[montyDoor] = "monty pick";
    } else {
      // Monty's pick will be the door the car is behind
      montyDoor = carDoor;
      doors[carDoor] = "car + monty pick";
    }

    //
    // Tracking!
    //
    if (chosenDoor !== carDoor) {
      // Switching caused a win
      wins++;
    } else {
      // Switching caused a loss
      losses++;
    }
  }

  console.log(`${wins} are the wins and ${losses} are the losses!`);
  console.log(`Switching resulted in a ${100 * (wins / runs)}% win rate!`);
  console.log("------------------------");
}

montyHallSimulation(20, 10000);

This example uses 20 doors as in my example from the earlier article, and the win rate for switching is indeed around 95%