64 lines
1.9 KiB
Kotlin
64 lines
1.9 KiB
Kotlin
package rps
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import kotlin.random.Random
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const val TURNS = 100
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val PLAYER_TWO_CHOICE = Move.ROCK
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fun main() {
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println("Outcome from Player 1’s perspective: ${playGame(TURNS)}")
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}
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/** Determine the [Outcome] of [first] vs [second] from the perspective of [first]. */
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fun determineOutcome(first: Move, second: Move): Outcome = when {
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first.strongAgainst() == second -> Outcome.WIN
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first == second -> Outcome.DRAW
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else -> Outcome.LOSS
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}
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// Note: This could be slightly more efficiently and directly on the Sequence
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// (but a lot less elegantly) with an imperative loop and three mutable integers.
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fun List<Outcome>.calculateGameSummary() = GameSummary(
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wins = count { it == Outcome.WIN },
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draws = count { it == Outcome.DRAW },
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losses = count { it == Outcome.LOSS },
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)
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fun playGame(turns: Int): GameSummary = generateSequence { randomMove() }
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.take(turns)
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.map { determineOutcome(it, PLAYER_TWO_CHOICE) }
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.toList()
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.calculateGameSummary()
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fun randomMove(): Move = Move.values().let { allMoves ->
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allMoves[Random.nextInt(allMoves.size)]
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}
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/*
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* Classes and named tuples below this point.
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* (All in the same file for easier reviewability in a web UI on Github/Gitea).
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*/
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/**
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* A possible move in a game of rock-paper-scissors.
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*
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* [strongAgainst] is a function for lazy evaluation because otherwise we can’t access SCISSORS before it’s been defined.
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* If the game needs to be expanded (e.g. the somewhat common “rock, paper, scissors, salamander, spock”),
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* this argument could be a List<Move> instead.
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*/
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enum class Move(val strongAgainst: () -> Move) {
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ROCK({ SCISSORS }),
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PAPER({ ROCK }),
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SCISSORS({ PAPER })
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}
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// purposely not calling this Result to avoid confusion with kotlin.Result and similar
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enum class Outcome {
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WIN,
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DRAW,
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LOSS
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}
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// Named Triple for readability
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data class GameSummary(val wins: Int, val draws: Int, val losses: Int)
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