66 lines
1.3 KiB
Markdown
66 lines
1.3 KiB
Markdown
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---
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id: 5900f5181000cf542c51002a
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challengeType: 5
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title: 'Problem 427: n-sequences'
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---
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## Description
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<section id='description'>
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A sequence of integers S = {si} is called an n-sequence if it has n elements and each element si satisfies 1 ≤ si ≤ n. Thus there are nn distinct n-sequences in total.
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For example, the sequence S = {1, 5, 5, 10, 7, 7, 7, 2, 3, 7} is a 10-sequence.
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For any sequence S, let L(S) be the length of the longest contiguous subsequence of S with the same value.
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For example, for the given sequence S above, L(S) = 3, because of the three consecutive 7's.
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Let f(n) = ∑ L(S) for all n-sequences S.
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For example, f(3) = 45, f(7) = 1403689 and f(11) = 481496895121.
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Find f(7 500 000) mod 1 000 000 009.
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</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>euler427()</code> should return 97138867.
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testString: 'assert.strictEqual(euler427(), 97138867, ''<code>euler427()</code> should return 97138867.'');'
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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 euler427() {
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// Good luck!
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return true;
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}
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euler427();
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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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