[TS] Swap two element in the array (mutation)

weixin_33971977

于 2017-10-03 18:39:00 发布

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文章标签： javascript ViewUI

本文介绍了一种简单现代的洗牌算法——费雪-耶茨洗牌算法，并提供了JavaScript/TypeScript实现。该算法确保每张牌出现在每个位置的概率相同，实现了真正的随机洗牌。

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Shuffling is a common process used with randomizing the order for a deck of cards. The key property for a perfect shuffle is that each item should have an equal probability to end up in any given index.

In this lesson we discuss the concept behind the simple modern fisher yates shuffle and implement it in JavaScript / TypeScript.

function randomInt(start: number, before: number) {
  return start + Math.floor(Math.random() * (before - start));
}

 function shuffle<T>(array: T[]): T[] {
  array = array.slice();

  for (let i = 0; i < array.length; i++) {
    const randomChoiceIndex = randomInt(i, array.length);
    [array[i], array[randomChoiceIndex]] = [array[randomChoiceIndex], array[i]]; // swap element in array
  }

  return array;
}