43 lines
780 B
Markdown
43 lines
780 B
Markdown
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---
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id: 5900f4411000cf542c50ff54
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title: 'Problem 213: Flea Circus'
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challengeType: 5
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forumTopicId: 301855
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dashedName: problem-213-flea-circus
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---
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# --description--
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A 30×30 grid of squares contains 900 fleas, initially one flea per square.
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When a bell is rung, each flea jumps to an adjacent square at random (usually 4 possibilities, except for fleas on the edge of the grid or at the corners).
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What is the expected number of unoccupied squares after 50 rings of the bell? Give your answer rounded to six decimal places.
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# --hints--
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`euler213()` should return 330.721154.
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```js
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assert.strictEqual(euler213(), 330.721154);
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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 euler213() {
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return true;
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}
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euler213();
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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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