70 lines
1.2 KiB
JavaScript
70 lines
1.2 KiB
JavaScript
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#!/usr/bin/js24
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function isPrime(num) {
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if (num === 3) {
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return true;
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}
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if (num % 2 === 0) {
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return false;
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}
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for (let i = 3; i <= Math.sqrt(num); i++) {
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if (num % i === 0) {
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return false;
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}
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}
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return true;
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}
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function findNextPrime(num) {
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while(!isPrime(++num)) {
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}
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return num;
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}
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function rightTruncatable(num, pset) {
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while (num > 9) {
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num = Math.floor(num/10);
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if (!pset.has(num)){
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return false;
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}
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}
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return true;
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}
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function leftTruncatable(num, pset) {
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while (num > 9) {
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exp = Math.pow(10, Math.floor(Math.log(num) / Math.log(10)));
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num -= Math.floor(num / exp) * exp;
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if (!pset.has(num)) {
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return false;
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}
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}
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return true;
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}
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let num = 7;
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let pset = new Set([2,3,5,7]);
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let tset = new Set();
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while(tset.size < 11) {
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num = findNextPrime(num);
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putstr('\rChecking '+num);
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pset.add(num);
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if (rightTruncatable(num, pset) && leftTruncatable(num, pset)) {
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tset.add(num);
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print('\r'+num+' ');
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}
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}
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print("Found 11 numbers, summing up.");
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let sum = 0;
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for (let number of tset) {
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print(number);
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sum += number;
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}
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print(sum);
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