ee1e8abd87
* feat(tools): add seed/solution restore script * chore(curriculum): remove empty sections' markers * chore(curriculum): add seed + solution to Chinese * chore: remove old formatter * fix: update getChallenges parse translated challenges separately, without reference to the source * chore(curriculum): add dashedName to English * chore(curriculum): add dashedName to Chinese * refactor: remove unused challenge property 'name' * fix: relax dashedName requirement * fix: stray tag Remove stray `pre` tag from challenge file. Signed-off-by: nhcarrigan <nhcarrigan@gmail.com> Co-authored-by: nhcarrigan <nhcarrigan@gmail.com>
47 lines
920 B
Markdown
47 lines
920 B
Markdown
---
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id: 5900f4421000cf542c50ff55
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title: 问题214个欧拉链
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challengeType: 5
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videoUrl: ''
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dashedName: problem-214-totient-chains
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---
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# --description--
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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。
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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：
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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
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这些链中只有两个以素数开头，它们的总和为12。
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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？
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# --hints--
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`euler214()`应该返回1677366278943。
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```js
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assert.strictEqual(euler214(), 1677366278943);
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```
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# --seed--
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## --seed-contents--
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```js
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function euler214() {
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return true;
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}
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euler214();
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```
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# --solutions--
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```js
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// solution required
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```
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