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49 lines
1.0 KiB
JavaScript
49 lines
1.0 KiB
JavaScript
const fs = require("fs");
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let [rules, messages] = fs
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.readFileSync("input", "utf-8")
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.trim()
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.split("\n\n")
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.map((part) => part.split("\n"));
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rules = rules
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.map((line) => line.split(": "))
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.map(([num, rule]) => [parseInt(num), rule])
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.sort((a, b) => a[0] - b[0])
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.map(([_, rule]) => rule);
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console.log(rules);
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console.log("=");
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// console.log(messages);
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function getRegex(idx) {
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const rule = rules[idx];
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if (rule.startsWith('"')) {
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return rule.slice(1, rule.length - 1);
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}
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let regex = "";
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let multiple = false;
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for (const symbol of rule.split(" ")) {
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if (symbol === "|") {
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regex = "(" + regex + "|";
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multiple = true;
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} else {
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regex = regex + getRegex(parseInt(symbol));
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}
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}
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regex = multiple ? regex + ")" : regex;
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rules[idx] = '"' + regex + '"';
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return regex;
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}
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const regex = new RegExp(`^${getRegex(0)}$`);
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console.log(rules);
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console.log(regex);
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let sum = 0;
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for (const message of messages) {
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if (regex.test(message)) sum++;
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}
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console.log(sum);
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