62 lines
1.8 KiB
Markdown
62 lines
1.8 KiB
Markdown
---
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id: 5900f3851000cf542c50fe98
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challengeType: 5
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videoUrl: ''
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title: 问题25：1000位斐波纳契数
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---
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## Description
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<section id="description"> Fibonacci序列由递归关系定义： <div style="padding-left: 4em;"> F <sub>n</sub> = F <sub>n-1</sub> + F <sub>n-2</sub> ，其中F <sub>1</sub> = 1且F <sub>2</sub> = 1。 </div>因此，前12个学期将是： <div style="padding-left: 4em; display: inline-grid; grid-template-rows: auto; row-gap: 7px;"><div> F <sub>1</sub> = 1 </div><div> F <sub>2</sub> = 1 </div><div> F <sub>3</sub> = 2 </div><div> F <sub>4</sub> = 3 </div><div> F <sub>5</sub> = 5 </div><div> F <sub>6</sub> = 8 </div><div> F <sub>7</sub> = 13 </div><div> F <sub>8</sub> = 21 </div><div> F <sub>9</sub> = 34 </div><div> F <sub>10</sub> = 55 </div><div> F <sub>11</sub> = 89 </div><div> F <sub>12</sub> = 144 </div></div>第12个学期F <sub>12</sub>是第一个包含三位数的术语。 Fibonacci序列中包含<var>n个</var>数字的第一项的索引是多少？ </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>digitFibonacci(5)</code>应该返回21。
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testString: assert.strictEqual(digitFibonacci(5), 21);
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- text: <code>digitFibonacci(10)</code>应该返回45。
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testString: assert.strictEqual(digitFibonacci(10), 45);
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- text: <code>digitFibonacci(15)</code>应该返回69。
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testString: assert.strictEqual(digitFibonacci(15), 69);
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- text: <code>digitFibonacci(20)</code>应该返回93。
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testString: assert.strictEqual(digitFibonacci(20), 93);
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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 digitFibonacci(n) {
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// Good luck!
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return n;
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}
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digitFibonacci(20);
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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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