2018-10-10 22:03:03 +00:00
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---
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id: 5900f3e61000cf542c50fef9
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2020-12-16 07:37:30 +00:00
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title: 问题122:有效取幂
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2018-10-10 22:03:03 +00:00
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challengeType: 5
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videoUrl: ''
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2021-01-13 02:31:00 +00:00
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dashedName: problem-122-efficient-exponentiation
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2018-10-10 22:03:03 +00:00
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---
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2020-12-16 07:37:30 +00:00
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# --description--
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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最简单的计算n15的方法需要十四次乘法:n×n×...×n = n15但是使用“二进制”方法可以在六次乘法中计算它:n×n = n2n2×n2 = n4n4×n4 = n8n8 ×n4 = n12n12×n2 = n14n14×n = n15然而,只能在五次乘法中计算它:n×n = n2n2×n = n3n3×n3 = n6n6×n6 = n12n12×n3 = n15我们将定义m (k)是计算nk的最小乘法数;例如m(15)= 5.对于1≤k≤200,找到Σm(k)。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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# --hints--
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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`euler122()`应返回1582。
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2018-10-10 22:03:03 +00:00
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```js
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2020-12-16 07:37:30 +00:00
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assert.strictEqual(euler122(), 1582);
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2018-10-10 22:03:03 +00:00
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```
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2021-01-13 02:31:00 +00:00
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# --seed--
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## --seed-contents--
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```js
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function euler122() {
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return true;
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}
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euler122();
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```
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2020-12-16 07:37:30 +00:00
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# --solutions--
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2020-08-13 15:24:35 +00:00
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2021-01-13 02:31:00 +00:00
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```js
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// solution required
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```
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