2018-10-10 22:03:03 +00:00
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---
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id: 5900f37a1000cf542c50fe8d
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2020-12-16 07:37:30 +00:00
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title: 问题14:最长的Collatz序列
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2018-10-10 22:03:03 +00:00
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challengeType: 5
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videoUrl: ''
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---
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2020-12-16 07:37:30 +00:00
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# --description--
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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为正整数集定义以下迭代序列:
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`n` → `n` / 2( `n`是偶数)
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`n` →3 `n` + 1( `n`为奇数)
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使用上面的规则并从13开始,我们生成以下序列:
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13→40→20→10→5→16→8→4→2→1
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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可以看出,该序列(从13开始并在1结束)包含10个项。虽然尚未证实(Collatz问题),但是认为所有起始数字都在1处结束。在给定`limit`下,哪个起始数产生最长链?注意:一旦链条启动,条款允许超过一百万。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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# --hints--
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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`longestCollatzSequence(14)`应该返回9。
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2018-10-10 22:03:03 +00:00
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```js
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2020-12-16 07:37:30 +00:00
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assert.strictEqual(longestCollatzSequence(14), 9);
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```
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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`longestCollatzSequence(5847)`应返回3711。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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```js
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assert.strictEqual(longestCollatzSequence(5847), 3711);
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2018-10-10 22:03:03 +00:00
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```
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2020-12-16 07:37:30 +00:00
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`longestCollatzSequence(46500)`应返回35655。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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```js
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assert.strictEqual(longestCollatzSequence(46500), 35655);
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```
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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`longestCollatzSequence(54512)`应返回52527。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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```js
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assert.strictEqual(longestCollatzSequence(54512), 52527);
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```
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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`longestCollatzSequence(1000000)`应返回837799。
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2018-10-10 22:03:03 +00:00
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```js
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2020-12-16 07:37:30 +00:00
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assert.strictEqual(longestCollatzSequence(100000), 77031);
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2018-10-10 22:03:03 +00:00
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```
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2020-08-13 15:24:35 +00:00
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2020-12-16 07:37:30 +00:00
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# --solutions--
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