45 lines
805 B
Markdown
45 lines
805 B
Markdown
---
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id: 5900f4e11000cf542c50fff3
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title: 'Problem 372: Pencils of rays'
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challengeType: 5
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forumTopicId: 302034
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dashedName: problem-372-pencils-of-rays
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---
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# --description--
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Let $R(M, N)$ be the number of lattice points ($x$, $y$) which satisfy $M \lt x \le N$, $M \lt y \le N$ and $\left\lfloor\frac{y^2}{x^2}\right\rfloor$ is odd.
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We can verify that $R(0, 100) = 3\\,019$ and $R(100, 10\\,000) = 29\\,750\\,422$.
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Find $R(2 \times {10}^6, {10}^9)$.
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**Note:** $\lfloor x\rfloor$ represents the floor function.
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# --hints--
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`pencilsOfRays()` should return `301450082318807040`.
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```js
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assert.strictEqual(pencilsOfRays(), 301450082318807040);
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```
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# --seed--
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## --seed-contents--
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```js
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function pencilsOfRays() {
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return true;
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}
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pencilsOfRays();
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```
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# --solutions--
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```js
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// solution required
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```
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