Problem of the Day
A new programming or logic puzzle every Mon-Fri

Blackjack Dealer

Today's goal is to build the AI for a blackjack dealer. A blackjack dealer has the following rules (taken from Wikipedia): "The dealer has to take hits until his or her cards total 17 or more points. (In some casinos, the dealer also hits on a "soft" 17—e.g., an initial ace and six.)". In our case we will be hitting on soft 17. Good luck!

Permalink: http://problemotd.com/problem/blackjack-dealer/

Comments:

  • bumbleguppy - 10 years, 2 months ago

    Funny enough, I have been working on a javascript/HTML card game. This is adapted from what I have so far.

        var CARD_DECK = [2,3,4,5,6,7,8,9,10,11,12,13,14,2,3,4,5,6,7,8,9,10,11,12,13,14,2,3,4,5,6,7,8,9,10,11,12,13,14,2,3,4,5,6,7,8,9,10,11,12,13,14];
var HIGH_CARD = 14;

//shuffles array, stolen from underscore.js
function shuffle(array) {
  var length = array.length;
  var i = 0;
  var shuffled = new Array(length);
  var rnd = Math.random;
  var floor = Math.floor;
  var rand = 0;
  for (; i < length; ++i) {
    rand = floor(rnd() * i);
    if (rand !== i) shuffled[i] = shuffled[rand];
    shuffled[rand] = array[i];
  }
  return shuffled;
}

function getBlackJackHandValue(faces) {
  var sum = 0;
  var ace = 0;
  var i = faces.length;
  while(i--) {
    if (faces[i] === HIGH_CARD) {
      ++ace;
      ++sum;
    } else {
      sum += faces[i] < 11 ? faces[i] : 10;
    }
  }
  while (ace--) {
    if (sum + 10 <= 21) {
      sum += 10;
    }
  }
  return sum;
}

function scoreHand(hand, lastDealt) {
  var score = getBlackJackHandValue(hand);
  var soft17 = (score === 17 && hand.indexOf(HIGH_CARD) > -1);
  var i = lastDealt;

  while (score < 17 || soft17) {
    ++i;
    hand.push(CARD_DECK[i]);
    score = getBlackJackHandValue(hand);
    soft17 = false;
  }

  return score;
}

function getDealerScore() {
  shuffle(CARD_DECK);
  var dealerHand = [CARD_DECK[0], CARD_DECK[1]];
  var result = scoreHand(dealerHand, 1);
  return result;
}

console.log(getDealerScore());

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