monty-hall.ts

const shuffle = (array: Array<any>) => {
  for (let i = array.length - 1; i > 0; i--) {
    const j = Math.floor(Math.random() * (i + 1))
    ;[array[i], array[j]] = [array[j], array[i]]
  }
  return array
}

const getDoors = (): Array<{ door: number; price: "car" | "goat" }> => {
  return shuffle(["car", "goat", "goat"]).map((price, door) => ({
    price,
    door,
  }))
}

const getChoice = (): number => {
  return Math.floor(Math.random() * 3)
}

const door = () => {
  const doors = getDoors()
  const choice = getChoice()

  const myDoor = doors[choice]
  const otherDoors = doors.filter((_v, i) => i !== choice)
  const goatDoor = otherDoors.find((v) => v.price === "goat")!
  const otherDoor = otherDoors.find((v) => v.door !== goatDoor.door)!

  return { myDoor, otherDoor }
}

const play = () => {
  let winWithNoChange = 0
  let winWithChangeDoor = 0
  for (let i = 0; i < 1e4; i++) {
    const { myDoor, otherDoor } = door()
    if (myDoor.price === "car") {
      winWithNoChange++
    } else {
      winWithChangeDoor++
    }
  }

  console.log(`winWithNoChange: ${winWithNoChange}`)
  console.log(`winWithChangeDoor: ${winWithChangeDoor}`)
}

play()