42 lines
1.2 KiB
TypeScript
42 lines
1.2 KiB
TypeScript
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const fs = require('fs');
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const input = fs.readFileSync(__dirname + '/input.txt', 'utf8');
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const rules: Array<[number, number]> = [];
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const updates: Array<Array<number>> = [];
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let rulesSection = true;
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input.split("\n").forEach((line: string) => {
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if (!line) {
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rulesSection = false;
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return;
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}
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if (rulesSection) {
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rules.push(line.split('|').map((s) => parseInt(s)) as [number, number]);
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} else {
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updates.push(line.split(',').map((s) => parseInt(s)));
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}
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});
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let result = 0;
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updates.forEach((update) => {
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let newUpdate: Array<number> = [];
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for (let page of update) {
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const relevantRules = rules.filter((rule) => rule[0] === page || rule[1] === page);
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let i = 0;
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for (; i < newUpdate.length; i++) {
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const otherPage = newUpdate[i];
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const rule = relevantRules.find((rule) => rule[0] === otherPage || rule[1] === otherPage);
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if (rule && rule[0] === page) {
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break;
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}
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}
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newUpdate = [...newUpdate.slice(0, i), page, ...newUpdate.slice(i)]
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}
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if (update.join(',') !== newUpdate.join(',')) {
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result += newUpdate[(newUpdate.length - 1) / 2];
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}
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});
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console.log(result);
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