73 lines
1.5 KiB
JavaScript
73 lines
1.5 KiB
JavaScript
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#!/usr/bin/js
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/*
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Copyright © 2017 Jörg Sommer <joerg@alea.gnuu.de>
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License: MIT https://opensource.org/licenses/MIT
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*/
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'use strict';
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//////
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//
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// Some monkey patching
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//
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if (typeof putstr === 'undefined')
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// in case of node.js
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var putstr = process.stdout.write.bind(process.stdout);
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if (typeof print === 'undefined')
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// in case of node.js
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var print = console.log.bind(console);
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//////
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//
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// Solution of Euler 37 https://projecteuler.net/problem=37
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//
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let primeNumbers = new Set([2,3,5,7,11,13,17,19]);
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function nextPrimeNumAfter(number) {
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while (true) {
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number += 2;
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for (var i = Math.floor(Math.sqrt(number)); i >= 3; --i) {
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if (number % i == 0)
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break;
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}
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if (i < 3)
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return number;
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}
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}
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function allSubnumsArePrime(num) {
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let rightSide = num % 10;
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let leftSide = Math.floor(num / 10);
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let factor = 1;
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while (leftSide > 0) {
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if (!(primeNumbers.has(leftSide) && primeNumbers.has(rightSide)))
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return false;
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factor *= 10;
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rightSide += (leftSide % 10) * factor;
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leftSide = Math.floor(leftSide / 10);
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}
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return true;
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}
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let sum = 0;
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let num = 19;
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for (let numCnt = 0; numCnt < 11; ) {
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num = nextPrimeNumAfter(num);
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primeNumbers.add(num);
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putstr('\rChecking ' + num);
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if (allSubnumsArePrime(num)) {
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print('\r' + num + ' ');
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sum += num;
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++numCnt;
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}
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}
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print('Answer: ' + sum);
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