83 lines
2.5 KiB
JavaScript
83 lines
2.5 KiB
JavaScript
const fs = require('fs');
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const path = require('path');
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function gcd(a, b) {
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while (b !== 0) {
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let t = b;
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b = a % b;
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a = t;
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}
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return a;
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}
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function lcm(a, b) {
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return (a * b) / gcd(a, b);
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}
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function parseFile(filePath) {
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console.log(`Parsing file: ${filePath}`);
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const data = fs.readFileSync(filePath, 'utf8').trim();
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const [stepsSection, rulesSection] = data.split('\n\n');
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const steps = stepsSection.split('').map(char => char === 'L' ? 0 : 1);
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const rules = rulesSection.split('\n').reduce((acc, line) => {
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const [state, directions] = line.split('=').map(s => s.trim());
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const [left, right] = directions.split(',').map(s => s.trim());
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acc['L'][state] = left.slice(1);
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acc['R'][state] = right.slice(0, -1);
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return acc;
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}, { 'L': {}, 'R': {} });
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return { steps, rules };
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}
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function navigateNetworkSimultaneously(steps, rules) {
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console.log("Starting navigation of network.");
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const startNodes = Object.keys(rules['L']).filter(node => node.endsWith('A'));
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let currentNodes = startNodes;
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let stepCount = 0;
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const timeToZ = {};
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while (Object.keys(timeToZ).length < startNodes.length) {
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currentNodes.forEach((node, index) => {
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const direction = steps[stepCount % steps.length] === 0 ? 'L' : 'R';
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const nextNode = rules[direction][node];
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currentNodes[index] = nextNode;
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if (nextNode.endsWith('Z') && !(index in timeToZ)) {
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timeToZ[index] = stepCount + 1;
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}
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});
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stepCount++;
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console.log(`Step ${stepCount}: Current nodes - ${currentNodes}`);
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}
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return Object.values(timeToZ).reduce((acc, val) => lcm(acc, val), 1);
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}
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function runTest() {
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console.log("Running test...");
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const testPath = path.join(__dirname, '../test.txt');
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const { steps, rules } = parseFile(testPath);
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const expected = 6;
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const result = navigateNetworkSimultaneously(steps, rules);
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if (result !== expected) {
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throw new Error(`Test failed: expected ${expected}, got ${result}`);
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}
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console.log(`Test passed with ${result} steps.`);
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}
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function main() {
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try {
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runTest();
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const inputPath = path.join(__dirname, '../input.txt');
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const { steps, rules } = parseFile(inputPath);
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const result = navigateNetworkSimultaneously(steps, rules);
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console.log(`All paths reached 'Z' nodes simultaneously in ${result} steps.`);
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} catch (error) {
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console.error(`Error: ${error.message}`);
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}
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}
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main();
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