javascript - 如何保证循环中随机出现一定次数？

Question

我有一个模拟时钟指针旋转的程序，它随机跳转正常旋转量的 2 倍。我需要保证在一个完整的轮换中，我至少会跳 n 次。我应该如何随机化它但确保至少 n 次跳跃？

我考虑过每 x 次迭代都有一个有保证的跳跃，但它不是随机的。

这是我的旋转循环的代码:

for (let i = 0; i < ticks; i++) {           
    // Move the clockhand by a position, sometimes by a greater amount 
    setTimeout(() => {
        let d = Math.random();
        jump = false;
        // Randomize and keep track of jumps
        if (d < (probabilty/100)) {
            jump = true;
        }
     }
}

Answer 1

一种方法是设置每次完整旋转的 MAX_JUMPS 和 MAX_TICKS 数量，然后跟踪每次迭代中执行的跳跃和滴答数量。如果跳跃和刻度仍未达到最大数量，则在它们之间随机选择。如果其中一个达到最大值，则只需选择另一个直到轮换完成。

这是一个工作示例，其中保证正好 5 跳转。请注意，我将 DISTANCE 设置为仅 30，因为代码段控制台不会显示很多行。此外，超时延迟设置为 0 只是为了快速显示完整结果。

const DISTANCE = 30 // change to 60
const MAX_JUMPS = 5
const MAX_TICKS = DISTANCE - 2 * MAX_JUMPS
const PROBABILITY = 0.25

let currentDistance = 0
let normalTicks = 0
let jumps = 0

function oneTick() {
  if (currentDistance === DISTANCE) {
    // Completed full rotation
    console.log('normalTicks = ', normalTicks, ', jumps = ', jumps)
    return
  }

  setTimeout(() => {
    if (normalTicks === MAX_TICKS) {
      // If we are out of normal ticks then just jump
      // to satisfy the MAX_JUMPS amount
      jump()

    } else if (jumps === MAX_JUMPS) {
      // If we run out of jumps, do normal tick
      normal()

    } else {
      // If both ticks and jumps are available then randomly choose one
      if (Math.random() > PROBABILITY) {
        normal()
      } else {
        jump()
      }
      
    }

    console.log(currentDistance)
    oneTick()
  }, 0 /* change to 1000 */)
}

function normal() {
  normalTicks += 1
  currentDistance += 1
}

function jump() {
  jumps += 1
  currentDistance += 2
  console.log('JUMPED! Jumps left: ', MAX_JUMPS - jumps)
}

oneTick()

.as-console-wrapper {
  min-height: 200px;
  top: 0;
}

编辑:要使其至少执行 MAX_JUMPS 并在之后随机执行更多跳跃，只需删除 if (jumps === MAX_JUMPS) 阻止:

const DISTANCE = 30 // change to 60
const MAX_JUMPS = 5
const MAX_TICKS = DISTANCE - 2 * MAX_JUMPS
const PROBABILITY = 0.25

let currentDistance = 0
let normalTicks = 0
let jumps = 0

function oneTick() {
  if (currentDistance >= DISTANCE) {
    console.log('normalTicks = ', normalTicks, ', jumps = ', jumps)
    return
  }

  setTimeout(() => {
    if (normalTicks === MAX_TICKS) {
      jump()
    } else {
      if (Math.random() > PROBABILITY) {
        normal()
      } else {
        jump()
      }
    }

    console.log(currentDistance)
    oneTick()
  }, 0 /* change to 1000 */ )
}

function normal() {
  normalTicks += 1
  currentDistance += 1
}

function jump() {
  jumps += 1
  currentDistance += 2
  console.log('JUMPED! Jumps performed: ', jumps)
}

oneTick()

.as-console-wrapper {
  min-height: 200px;
  top: 0;
}

请注意，这可能会导致它在旋转的最后一个刻度处跳跃，因此您必须决定是否应将其计为单个刻度，或者是否应将额外的刻度添加到下一个旋转中。