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Daily Challenge #128 - Blackjack Scorer

dev.to staff on November 30, 2019

Write a function that determines the score of a hand in a standard game of Blackjack 21. The function will receive an array of strings representing...

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edh_developer • Nov 30 '19

Python, with a couple assumptions:

["A","10","A"] should return 12, not 22.
If the function is supposed to say "busted", it would have to do that before returning the corresponding numerical value.


def score(cards):
  facecards = ["K","Q","J"]
  total = 0
  aces = 0

  for c in cards:
    if c in facecards:
      total += 10
    elif c == "A":
      total += 11
      aces += 1
    else:
      total += int(c)


  for _ in range(aces):
    if total > 21:
      total -= 10

  if total > 21:
    print "Busted!"

  return total

Vladimir Ignatev • Nov 30 '19 • Edited

My solution uses itertools.product to compute possible variations of Ace counting.

from itertools import product


def score(hand):
    royalty = ('J', 'Q', 'K',)
    ace = ('A',)
    aces = 0
    _score = 0

    for card in hand:
        if card in royalty:
            _score += 10
        elif card not in ace:
            _score += int(card)
        else:
            aces += 1

    if aces == 0:
        return _score

    aces_combinations = []

    variations = [_score + sum(ace_values) for ace_values in product((1,11), repeat=aces)]

    variations_vs_delta = [abs(21 - _s) for _s in variations]
    return variations[variations_vs_delta.index(min(variations_vs_delta))]


def bj_score(hand):
    s = score(hand)
    if s > 21:
        print 'Busted!'
    return s



cases = [
    ["A"],
    ["A", "J"],
    ["A", "10", "A"],
    ["5", "3", "7"],
    ["5", "4", "3", "2", "A", "K"]
]

for case in cases:
    print(case)
    print(bj_score(case))

edh_developer • Nov 30 '19

"closest to 21"? I'm guessing you mean "Closest to 21 without going over. If it's not possible to prevent going over, return the lowest score possible."

Is that correct?