darts.ts

const start = [
  1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20,
]

export function score(data: number[]): number {
  let score = 0
  for (let i = 0; i < data.length; i++) {
    score += Math.abs(data[i]! - data[(i + 1) % data.length]!)
  }
  return score
}

export function randint(max: number): number {
  return Math.floor(max * Math.random())
}

export function go(
  data: number[],
  acceptChance = 0.3,
  count = 10000,
): { data: number[]; scores: number[]; i: number } {
  let a = 0
  let b = 0
  let temp = 0
  let next = 0
  let current = score(data)
  const scores: number[] = []

  let i = 0
  for (; i < count; i++) {
    a = randint(data.length)
    b = randint(data.length)
    // unconditionally accept sometimes
    if (Math.random() < acceptChance) {
      temp = data[b]!
      data[b] = data[a]!
      data[a] = temp
      current = score(data)
    } else {
      // check the new score
      temp = data[b]!
      data[b] = data[a]!
      data[a] = temp
      next = score(data)
      // if the score got smaller, undo the swap
      if (next < current) {
        temp = data[b]!
        data[b] = data[a]!
        data[a] = temp
      } else {
        // store the score
        current = next
      }
    }
    scores.push(current)
    if (current == 200) {
      return { data, scores, i }
    }
  }

  return { data, scores, i }
}