140 lines
3.7 KiB
JavaScript
140 lines
3.7 KiB
JavaScript
import { readFileSync } from 'node:fs';
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const input = readFileSync('input', 'utf-8');
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class Monkey {
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constructor(monkeys, name) {
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this.monkeys = monkeys;
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this.name = name;
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this.value = undefined;
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this.formulas = [];
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this.aliases = [];
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}
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addFormula(left, operator, right) {
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this.formulas.push([left, operator, right]);
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return this;
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}
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removeFormulasInvolving(name) {
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this.formulas = this.formulas.filter(
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([left, _, right]) => left !== name && right !== name
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);
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return this;
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}
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addAlias(name) {
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this.aliases.push(name);
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return this;
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}
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setValue(value) {
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this.value = value;
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return this;
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}
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solve(path = []) {
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if (this.value !== undefined) {
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return this.value;
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}
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for (const name of this.aliases) {
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if (path.includes(name)) {
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continue;
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}
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const value = this.monkeys[name].solve([...path, this.name]);
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if (value !== 'UNKNOWN') {
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return value;
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}
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}
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for (const [left, operator, right] of this.formulas) {
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if (path.includes(left) || path.includes(right)) {
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continue;
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}
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const leftValue = this.monkeys[left].solve([...path, this.name]);
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const rightValue = this.monkeys[right].solve([...path, this.name]);
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if (leftValue === 'UNKNOWN' || rightValue === 'UNKNOWN') {
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continue;
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}
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switch (operator) {
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case '*': return leftValue * rightValue;
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case '/': return leftValue / rightValue;
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case '+': return leftValue + rightValue;
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case '-': return leftValue - rightValue;
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}
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}
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return 'UNKNOWN';
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}
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}
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const monkeys = {};
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function getMonkey(name) {
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if (!monkeys.hasOwnProperty(name)) {
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monkeys[name] = new Monkey(monkeys, name)
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}
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return monkeys[name];
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}
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input
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.split('\n')
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.filter(line => !!line.trim())
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.forEach(line => {
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const match = line.match(/^(\w+):\s+(.+?)\s*$/);
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if (!match) {
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throw new Error(`Invalid monkey: ${line}`);
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}
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const name = match[1];
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const job = match[2];
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if (/^\d+$/.test(job)) {
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getMonkey(name).setValue(parseInt(job));
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} else {
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const match = job.match(/^(\w+)\s*([*\/+\-=])\s*(\w+)$/);
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if (!match) {
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throw new Error(`Invalid formula: ${formula}`);
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}
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const left = match[1];
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const operator = match[2];
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const right = match[3];
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switch (operator) {
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case '*':
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getMonkey(name).addFormula(left, '*', right);
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getMonkey(left).addFormula(name, '/', right);
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getMonkey(right).addFormula(name, '/', left);
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break;
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case '/':
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getMonkey(name).addFormula(left, '/', right);
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getMonkey(left).addFormula(name, '*', right);
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getMonkey(right).addFormula(left, '/', name);
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break;
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case '-':
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getMonkey(name).addFormula(left, '-', right);
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getMonkey(left).addFormula(name, '+', right);
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getMonkey(right).addFormula(left, '-', name);
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break;
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case '+':
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getMonkey(name).addFormula(left, '+', right);
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getMonkey(left).addFormula(name, '-', right);
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getMonkey(right).addFormula(name, '-', left);
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break;
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default:
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throw new Error(`Invalid operator: ${operator}`);
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}
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}
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});
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const rootYells = monkeys['root'].solve();
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console.log('The root monkey will yell:', rootYells);
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for (const monkey of Object.values(monkeys)) {
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monkey.removeFormulasInvolving('root');
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}
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const {0: left, 2: right} = monkeys['root'].formulas[0];
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monkeys[left].addAlias(right);
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monkeys[right].addAlias(left);
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const humnYells = monkeys['humn'].setValue(undefined).solve();
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console.log('To pass roots equality test, yell:', humnYells);
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