Rate this post


This question is from the book Daily Coding Problem, and is a slightly modified version of the problem described in this MIT video. The question is as follows:

Blackjack is a two player card game whose rules are as follows:

  • The player and then the dealer are each given two cards.
  • The player can then “hit”, or ask for arbitrarily many additional cards, so as his or her total does not exceed 21.
  • The dealer must then hit if his or her total is 16 or lower, otherwise pass.
  • Finally, the two compare totals, and the one with the greatest sum not exceeding 21 is the winner.

For this problem, we simplify the card values to be as follows: each
card between 2 and 10 counts as their face value, face cards count as
10, and aces count as 1.

Given perfect knowledge of the sequence of cards in the deck,
implement a blackjack solver that maximizes the player’s score (that
is, wins minus losses).

The book has the following code:

import random


class Deck:
    def __init__(self, seed=None):
        self.cards = [i for i in range(1, 10)] * 4 + [10] * 16
        random.seed(seed)
        random.shuffle(self.cards)

    def deal(self, start, n):
        return self.cards[start:start + n]


class Player:
    def __init__(self, hand):
        self.hand = hand
        self.total = 0

    def deal(self, cards):
        self.hand.extend(cards)
        self.total = sum(self.hand)


def cmp(x, y):
    return (x > y) - (x  21:
            results.append((-1, count))
            break

        while dealer.total  21:
            results.append((1, count))
        else:
            results.append((cmp(player.total, dealer.total), count))

    options = []
    for score, next_start in results:
        options.append(score +
                       scores[next_start] if next_start 

Basically, for a suffix of the deck starting at card n (1 0 to 52 - n hits, until they go bust, and then the dealer taking hits as long as their score is

For each iteration of the loop for i in range(49 - start), the count = “number of cards used” is reset to start + 4, which makes sense since we are simulating the player taking a different number of hits than last time. However, what troubles me is the player and the dealer’s hands are not reset. In my mind, for each iteration of that loop, we should start with the player and dealer having been dealt two cards each, and not retain the last hand.

Am I understanding this right?