The Monty Hall Problem

The Monty Hall Problem JS Codes

// Made by Mei Weng Brough-Smyth
// https://www.beepboop.com.au/2014/05/the-monty-hall-problem.html

var doorSelected;
var willSwitch;
var noOfGames;
var input;

var doorOpened = 0;
var timesWon = 0;
var totalGames = 0;

var consoleOut = document.getElementById("console");

function newGame() {
  // Get WillSwitch input
  willSwitch = (document.getElementById("switch").checked)? true : false;
  
  // Get Radio input
  var radios = document.getElementsByName('door');
  for (var i = 0, length = radios.length; i < length; i++)   {
    if (radios[i].checked) {
        doorSelected = radios[i].value;
        break;
    }
  }
  if (doorSelected === "Randomise!") {
    doorSelected = Math.floor(Math.random() * 3);
  }
  doorSelected = parseInt(doorSelected, 10);
  
  // Get number of Games
  input = document.getElementById('input').value;
  noOfGames = input.match(/^\d+$/);
  
  // Get random winning door
  var winningDoor = Math.floor(Math.random() * 3);

  // Initialise game
  var game = [false, false, false];
  game[winningDoor] = true;
  
  // Initialise player perspective
  var player = [null, null, null];
  
  player[doorSelected] = "doorSelected";
  
  // Door select output
  doorSelectedOut = doorSelected + 1;
  consoleOut.innerHTML += "You select door " + doorSelectedOut + ".<br>";
  
  // Find door door to open
  doorOpened = doorSelected + 1;
  if (doorOpened > 2) { //If it's too high, bring it back down into our array
     doorOpened = doorOpened - 3;
  }
  if (game[doorOpened] === true) { //Move opened door along if it's the winning door
     doorOpened++;
  }
  
  // Door opened output and append to player array
  doorOpenedOut = doorOpened + 1;
  consoleOut.innerHTML += "Door " + doorOpenedOut + " is opened to reveal nothing.<br>";
  player[doorOpened] = "doorOpened";
  
  if (willSwitch === true) {
    for (var j = 0; j < player.length; j++) {
      if (player[j] === null) {
        // Get player to switch to null in player array and output
        jOut = j+1;
        consoleOut.innerHTML += ("You switch to door " + jOut + ".<br>");
        if (game[j] === true) {
          timesWon++; // Check if switched door is this winning door
          consoleOut.innerHTML += ("<b>You win!<br></b>");
        } else {
          consoleOut.innerHTML += ("<b>You lose.<br></b>");
        }
      }
    }
  } else {
    for (var k = 0; k < player.length; k++) {
      if (player[k] === "doorSelected") {
        consoleOut.innerHTML += "You stick with " + doorSelectedOut + "<br>";
        if (game[doorSelected] === true) {
          timesWon++; // Check if initial door is this winning door
          consoleOut.innerHTML += ("<b>You win!<br></b>");
        } else {
          consoleOut.innerHTML += ("<b>You lose.<br></b>");
        }
      }
    }
  }
  
  console.log(game);
  console.log(player);
  
  totalGames++;
  
  percentageWon = (timesWon/totalGames*100).toFixed(0) + "%";
  document.getElementById("wins").innerHTML = "Total wins: " + timesWon;
  document.getElementById("totalGames").innerHTML = "Total games: " + totalGames;
  document.getElementById("winRate").innerHTML = "Win rate: " + percentageWon;
  consoleOut.innerHTML += "----------------------------------------------------------<br>";
  if (totalGames < noOfGames) {
    newGame();
  } else {
    consoleOut.innerHTML += "<b>End game number " + totalGames + "! \\(^w^)/ </b><br>";
    reset();
  }
}

function reset() {
  timesWon = 0;
  totalGames = 0;
  consoleOut.scrollTop = consoleOut.scrollHeight;
}

function beepboop() {
  consoleOut.innerHTML = "";
  document.getElementById("console").innerHTML = "Suppose you're on a game show, and you're given the choice of three doors: Behind one door is a car; behind the others, goats. You pick a door, say No. 1, and the host, who knows what's behind the doors, opens another door, say No. 3, which has a goat. He then says to you, \"Do you want to pick door No. 2?\" Is it to your advantage to switch your choice?<br><a href=\"http://en.wikipedia.org/wiki/Monty_Hall_problem\">http://en.wikipedia.org/wiki/Monty_Hall_problem</a>";
  document.getElementById("wins").innerHTML = "┗(-_-)┛┏(-_-)┓┏(-_-)┛┗(-_- )┓┗(-_-)┛┏(-_-)┓";
  document.getElementById("totalGames").innerHTML = "┏(-_-)┓┏(-_-)┛┗(-_- )┓┗(-_-)┛┏(-_-)┓┏(-_-)┛";
  document.getElementById("winRate").innerHTML = "┗(-_-)┛┏(-_-)┓┏(-_-)┛┏(-_-)┓";
}