56 lines
1.3 KiB
Markdown
56 lines
1.3 KiB
Markdown
---
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id: 5900f5431000cf542c510056
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challengeType: 5
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videoUrl: ''
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title: 问题471：以椭圆形刻的三角形
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---
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## Description
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<section id="description">三角形ΔABC刻在椭圆中，方程为$ \ frac {x ^ 2} {a ^ 2} + \ frac {y ^ 2} {b ^ 2} = 1 $，0 <2b <a，a和b整数。设r（a，b）为内圆（2b，0）时A的圆周半径，A有坐标$ \ left（\ frac a 2，\ frac {\ sqrt 3} 2 b \ right） $。例如，r（3,1）= 1/2，r（6,2）= 1，r（12,3）= 2。 <p>设$ G（n）= \ sum <em>{a = 3} ^ n \ sum</em> {b = 1} ^ {\ lfloor \ frac {a - 1} 2 \ rfloor} r（a，b）$给你G（ 10）= 20.59722222，G（100）= 19223.60980（舍入为10位有效数字）。找到G（1011）。以科学计数法给出答案四舍五入到10位有效数字。使用小写e分隔尾数和指数。对于G（10），答案应该是2.059722222e1。 </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>euler471()</code>应返回1.895093981e + 31。
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testString: assert.strictEqual(euler471(), 1.895093981e+31);
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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 euler471() {
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// Good luck!
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return true;
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}
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euler471();
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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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