88 lines
2.3 KiB
Markdown
88 lines
2.3 KiB
Markdown
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---
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title: Babbage problem
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id: 594db4d0dedb4c06a2a4cefd
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localeTitle: 594db4d0dedb4c06a2a4cefd
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challengeType: 5
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---
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## Description
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<section id='description'>
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<p> <a href="https://en.wikipedia.org/wiki/Charles_Babbage" title="wp: Charles_Babbage">Charles Babbage</a> , mirando el tipo de problemas que su motor analítico podría resolver, dio este ejemplo: </p>
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<blockquote> What is the smallest positive integer whose square ends in the digits 269,696?</blockquote>
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<p> - Babbage, carta a Lord Bowden, 1837; ver Hollingdale y Tootill, <i>Electronic Computers</i> , segunda edición, 1970, pág. 125. </p>
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<p> Pensó que la respuesta podría ser 99,736, cuyo cuadrado es 9,947,269,696; pero no podía estar seguro. </p>
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<p> La tarea es averiguar si Babbage tuvo la respuesta correcta. </p>
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<p> Implemente una función para devolver el entero más bajo que satisfaga el problema de Babbage. Si Babbage tenía razón, devuelve el número de Babbage. </p>
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</section>
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## Instructions
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<section id='instructions'>
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</section>
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## Tests
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<section id='tests'>
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```yml
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tests:
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- text: <code>babbage</code> es una función.
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testString: 'assert(typeof babbage === "function", "<code>babbage</code> is a function.");'
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- text: ' <code>babbage(99736, 269696)</code> no debe devolver 99736 (hay una respuesta más pequeña).'
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testString: 'assert.equal(babbage(babbageAns, endDigits), answer, "<code>babbage(99736, 269696)</code> should not return 99736 (there is a smaller answer).");'
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='js-seed'>
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```js
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function babbage (babbageNum, endDigits) {
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// Good luck!
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return true;
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}
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```
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</div>
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### After Test
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<div id='js-teardown'>
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```js
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console.info('after the test');
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```js
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function babbage (babbageAns, endDigits) {
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const babbageNum = Math.pow(babbageAns, 2);
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const babbageStartDigits = parseInt(babbageNum.toString().replace('269696', "));
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let answer = 99736;
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// count down from this answer and save any sqrt int result. return lowest one
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for (let i = babbageStartDigits; i >= 0; i--) {
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const num = parseInt(i.toString().concat('269696'));
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const result = Math.sqrt(num);
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if (result === Math.floor(Math.sqrt(num))) {
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answer = result;
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}
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}
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return answer;
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}
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```
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</section>
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