79 lines
1.7 KiB
JavaScript
Executable file
79 lines
1.7 KiB
JavaScript
Executable file
#!/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 87 https://projecteuler.net/problem=87
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//
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if (Array.from) {
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// node.js
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Array.prototype.uniq = function() {
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return Array.from(new Set(this));
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};
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} else {
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// Spider monkey
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Array.prototype.uniq = new Function('return [...new Set(this)];');
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}
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// print([1,2,3,2,1].uniq());
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Array.prototype.cross = function (other, op) {
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let ret = [];
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for (let a of this) {
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for (let b of other) {
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ret.push(op(a, b));
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}
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}
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return ret;
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};
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// print([1, 2].cross([3, 4], (a, b) => a + b));
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let primeNumbers = [2,3,5,7,11,13,17,19];
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const limit = 5e7;
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for (let num = primeNumbers[primeNumbers.length - 1] + 2;
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num <= Math.sqrt(limit); num += 2) {
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for (var i = Math.floor(Math.sqrt(num)); i >= 3; --i) {
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if (num % i == 0)
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break;
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}
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if (i < 3)
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primeNumbers.push(num);
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}
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print('There are ' + primeNumbers.length + ' prime numbers below sqrt(50.000.000)');
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function pnPower(exp) {
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return primeNumbers.filter(x => x <= Math.pow(limit, 1 / exp))
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.map(x => Math.pow(x, exp));
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}
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// print(pnPower(4));
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let answ = pnPower(2).cross(pnPower(3), (a, b) => a + b)
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.filter(x => x < limit)
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.cross(pnPower(4), (a, b) => a + b)
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.filter(x => x < limit)
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.uniq()
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.length;
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print('Answer: ' + answ);
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