56 lines
1.2 KiB
Markdown
56 lines
1.2 KiB
Markdown
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---
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id: 5900f4421000cf542c50ff55
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challengeType: 5
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title: 'Problem 214: Totient Chains'
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videoUrl: ''
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localeTitle: 问题214个欧拉链
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---
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## Description
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<section id="description">设φ是欧拉的函数，即对于自然数n，φ（n）是k的数，1≤k≤n，gcd（k，n）= 1。 <p>通过迭代φ，每个正整数产生以1结尾的数字递减的链。例如，如果我们从5开始，则生成序列5,4,2,1。以下列出了长度为4的所有链条： </p><p> 5,4,2,1 7,6,2,1 8,4,2,1 9,6,2,1 10,4,2,1 12,4,2,1 14,6,2,1 18 ，6,2,1 </p><p>这些链中只有两个以素数开头，它们的总和为12。 </p><p>所有小于40000000的素数的总和是多少，它产生一个长度为25的链？ </p></section>
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## Instructions
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<section id="instructions">
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</section>
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## Tests
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<section id='tests'>
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```yml
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tests:
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- text: <code>euler214()</code>应该返回1677366278943。
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testString: 'assert.strictEqual(euler214(), 1677366278943, "<code>euler214()</code> should return 1677366278943.");'
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='js-seed'>
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```js
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function euler214() {
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// Good luck!
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return true;
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}
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euler214();
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```js
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// solution required
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```
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</section>
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