47 lines
1.0 KiB
Markdown
47 lines
1.0 KiB
Markdown
---
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id: 5900f5001000cf542c510013
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title: 'Problem 403: Lattice points enclosed by parabola and line'
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challengeType: 5
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forumTopicId: 302071
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dashedName: problem-403-lattice-points-enclosed-by-parabola-and-line
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---
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# --description--
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For integers $a$ and $b$, we define $D(a, b)$ as the domain enclosed by the parabola $y = x^2$ and the line $y = ax + b: D(a, b) = \\{ (x, y) | x^2 ≤ y ≤ ax + b \\}$.
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$L(a, b)$ is defined as the number of lattice points contained in $D(a, b)$. For example, $L(1, 2) = 8$ and $L(2, -1) = 1$.
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We also define $S(N)$ as the sum of $L(a, b)$ for all the pairs ($a$, $b$) such that the area of $D(a, b)$ is a rational number and $|a|,|b| ≤ N$.
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We can verify that $S(5) = 344$ and $S(100) = 26\\,709\\,528$.
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Find $S({10}^{12})$. Give your answer $\bmod {10}^8$.
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# --hints--
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`latticePoints()` should return `18224771`.
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```js
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assert.strictEqual(latticePoints(), 18224771);
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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 latticePoints() {
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return true;
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}
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latticePoints();
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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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