Estimates the minimum, maximum, and average number of turns in a game of Chutes and Ladders.

chutes.scala

object Chutes {
  val adjust = Map(
     1 -> 38,   4 -> 14,  9 -> 31, 16 ->  6, 21 -> 42, 28 -> 84, 36 -> 44,
    48 -> 26,  49 -> 11, 51 -> 67, 56 -> 53, 62 -> 19, 64 -> 60, 71 -> 91,
    80 -> 100, 87 -> 24, 93 -> 73, 95 -> 75, 98 -> 78
  )
  val rand = new util.Random
  val runCount = 10000

  @annotation.tailrec
  def play(pos: Int, turns: Int): Int =
    if (pos == 100) turns
    else {
      val next = pos + rand.nextInt(6) + 1
      if (next > 100) play(pos, turns + 1)
      else play(adjust.getOrElse(next, next), turns + 1)
    }

  def main(args: Array[String]): Unit = {
    val runs = (1 to runCount).map { _ => play(0, 0) }
    val avg = runs.sum.toDouble / runCount

    println(f"Average of $runCount runs is $avg%.2f")
    println(f"Max turns was ${runs.max}")
    println(f"Min turns was ${runs.min}")
  }
}

Most instructions specify that an exact spin is required to win, but none specify what happens if the spin is not exact... except the following:

Chutes and Ladders instructions, ca. 1978

This program includes adjustments for gameplay according to these instructions, notably the following:

• The initial position is just off the board, designated square 0.
• Only an exact spin to land on square 100 win. Spins landing beyond square 100 are ignored and play passes to the next player.