王荣吉占摸牌期望

scratch.kts

main()

fun main() {
    val testResult = mutableListOf<Int>()
    repeat(10000) {
        testResult.add(jiZhan())
    }
    val counts = testResult.groupingBy { it }.eachCount()
    var expect = 0f
    for ((number, count) in counts) {
        val probability = count.toFloat() / testResult.size
        expect += number * probability
    }
    println("Average is ${testResult.sum().toFloat() / testResult.size}, Expectation is $expect")
}

fun generateCards(containMNLM: Boolean = true): MutableList<Int> {
    val cards = mutableListOf<Int>()
    for (num in 1..13) {
        // 每个点数都有3*4张+额外的2点和12点共4张
        repeat(12) {
            cards.add(num)
        }
        if (num == 2 || num == 12) {
            cards.add(num)
            cards.add(num)
        }
    }
    if (containMNLM) {
        // 木牛流马的点数是5
        cards.add(5)
    }
    return cards
}

fun jiZhan(): Int {
    val cards = generateCards().shuffled()
    val resultCards = mutableListOf<Int>()
    for (i in cards.indices) {
        resultCards.add(cards[i])
        val guessBig = makeGuess(cards[i])
        if (guessBig && cards[i + 1] > cards[i]) {
            continue
        } else if (guessBig.not() && cards[i + 1] < cards[i]) {
            continue
        } else {
            resultCards.add(cards[i+1])
//            println("Wrong guess of $guessBig. Last card is ${cards[i]}, current card is ${cards[i + 1]}")
            break
        }
    }
//    println("Jizhan is over. Got ${resultCards.size} cards.")
    return resultCards.size
}

// true表示猜大
fun makeGuess(currentCardNum: Int, threshold: Int = 7): Boolean {
    return when (currentCardNum) {
        in 1..threshold -> {
            true
        }

        else -> {
            false
        }
    }
}