2018-10-10 18:03:03 -04:00
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---
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id: 5900f4e61000cf542c50fff9
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2020-12-16 00:37:30 -07:00
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title: 问题378:三角形三元组
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2018-10-10 18:03:03 -04:00
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challengeType: 5
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videoUrl: ''
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2021-01-13 03:31:00 +01:00
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dashedName: problem-378-triangle-triples
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2018-10-10 18:03:03 -04:00
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---
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2020-12-16 00:37:30 -07:00
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# --description--
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2018-10-10 18:03:03 -04:00
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2020-12-16 00:37:30 -07:00
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设T(n)为第n个三角形数,因此T(n)=
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2018-10-10 18:03:03 -04:00
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2020-12-16 00:37:30 -07:00
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n(n + 1)2
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2018-10-10 18:03:03 -04:00
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2020-12-16 00:37:30 -07:00
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。
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2018-10-10 18:03:03 -04:00
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2020-12-16 00:37:30 -07:00
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设dT(n)为T(n)的除数。例如:T(7)= 28且dT(7)= 6。
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2018-10-10 18:03:03 -04:00
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2020-12-16 00:37:30 -07:00
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令Tr(n)为三元组数(i,j,k),使得1≤i<j <k≤n且dT(i)> dT(j)> dT(k)。 Tr(20)= 14,Tr(100)= 5772,Tr(1000)= 11174776。
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2018-10-10 18:03:03 -04:00
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2020-12-16 00:37:30 -07:00
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找Tr(60 000 000)。给出答案的最后18位数字。
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2018-10-10 18:03:03 -04:00
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2020-12-16 00:37:30 -07:00
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# --hints--
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2018-10-10 18:03:03 -04:00
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2020-12-16 00:37:30 -07:00
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`euler378()`应该返回147534623725724700。
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2018-10-10 18:03:03 -04:00
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```js
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2020-12-16 00:37:30 -07:00
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assert.strictEqual(euler378(), 147534623725724700);
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2018-10-10 18:03:03 -04:00
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```
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2020-08-13 17:24:35 +02:00
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2021-01-13 03:31:00 +01:00
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# --seed--
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## --seed-contents--
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```js
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function euler378() {
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return true;
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}
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euler378();
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```
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2020-12-16 00:37:30 -07:00
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# --solutions--
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2021-01-13 03:31:00 +01:00
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```js
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// solution required
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```
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