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Three-Card Game: Deal Hands, Rank Them, Then Add a Flush Category

OpenAISoftware Engineer · Technical Screen
MediumSoftware EngineerTechnical ScreenSoftware Engineering Fundamentals

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A two-part card game coding exercise: deal three cards to each player from one deck, show every hand and pick the winner using three of a kind, pair and high card, then add a flush category between them. It tests hand representation, within-category comparison, tie handling and code that extends cleanly when a rule changes.

Implement a small card game. Each player is dealt three cards from one shuffled standard 52-card deck (13 ranks in each of 4 suits). After the deal, the program must report which three cards each player received and which player wins, according to the hand-ranking rules below.

The task has two parts. Part 1 uses three hand categories and ignores suits. Part 2 adds a fourth category that depends on suits, so write Part 1 in a way you can extend.

Constraints and Clarifications

  • Cards are dealt without replacement from a single deck, so no card appears twice in a round.
  • Unless you agree otherwise, ranks from lowest to highest are 2, 3, 4, 5, 6, 7, 8, 9, 10, J, Q, K, A, and the ace is always high.
  • Only the categories listed in the current part exist. There are no straights.
  • Two hands in the same category are compared as follows: three of a kind by the rank of the three cards; a pair by the rank of the pair first, and only then by the remaining card; any other hand by its highest card, then its second-highest, then its lowest.

Clarifying Questions

  • How many players are in a round, and is that number fixed or a parameter? (One deck supports at most 17 players with three cards each.)
  • If two or more players hold hands of exactly equal strength, is it a shared win, or is there a further tie-break such as suit order?
  • In what form should the result be reported: printed lines, a returned value, or both?
  • Is the ace always high, or can it also count as the lowest card?
  • Should the deal be reproducible, for example from a seed, so that the game can be tested?

Part 1 — Three categories, suits ignored

Hand categories from strongest to weakest:

  1. Three of a kind: all three cards have the same rank.
  2. Pair: exactly two of the cards share a rank.
  3. High card: any other hand.

Suits play no role in this part. Deal the hands, show each player's cards, and report the winner.

What This Part Should Cover

  • A card and deck representation with a numeric rank order and a deal without replacement
  • Detection of three of a kind, pair and high card
  • A within-category comparison that decides pairs by the pair before the leftover card
  • Reporting each player's hand and the winner, including what happens on an exact tie

Part 2 — Add the flush

Add a new category:

  • Flush: all three cards have the same suit.

The ranking from strongest to weakest becomes three of a kind > flush > pair > high card. Two flushes are compared by their highest card, then their second-highest, then their lowest. Update the program so that it deals, shows the hands and picks the winner under the new rules.

What This Part Should Cover

  • Flush detection and its placement between three of a kind and pair
  • Whether any hand can match two categories, and how the order of checks handles that
  • How much Part 1 code had to change, and whether the ranking is defined in one place
  • Tests showing a flush beating a pair under Part 2 but not under Part 1

Hints

Hint 1

Make hands comparable in one step: Look for a single value you can compute for each hand so that deciding which of two hands is stronger takes one comparison, covering both the category and the order within the category.

Hint 2

Mind the pair comparison: Two pair hands are decided by the paired rank before the leftover card. Check that the way you represent a pair hand puts its cards in the order in which they matter.

Hint 3

Check how the categories interact: Before writing the flush check, work out whether a three-card hand from one deck can be both a flush and a pair, or both a flush and three of a kind, and what that means for the order of your checks.

Hint 4

Locate the ranking: Look at where the category order lives in your Part 1 code. If inserting a category between two existing ones means editing several places, restructure it so that the order is defined once.

Follow-up questions

  • Add a straight (three consecutive ranks). Where would it rank, and how do you treat the ace if both A-2-3 and Q-K-A should count?
  • The game now shuffles two decks together. Which of your assumptions break? For example, can a hand now be three of a kind and a flush at the same time?
  • How would you test the winner logic without depending on random deals?
  • Many rounds are played and each player's number of wins must be tracked. What changes in your design?