Day 5

day5.peggy

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+manual = @order "\n" @pages
+
+order = (@num "|" @num "\n")*
+
+pages = (@page "\n")+
+
+page = num|1.., ","|
+
+num = n:$[0-9]+ { return parseInt(n, 10) }
+_ = [ \t]+

day5.ts

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+import { type MainArgs, parseFile } from './lib/utils.ts';
+
+type Parsed = [[number, number][], number[][]];
+
+function part1(inp: number[][][]): number {
+  return inp
+    .filter(([before, after]) => before.join(',') === after.join(','))
+    .reduce((t, [before]) => t + before[Math.floor(before.length / 2)], 0);
+}
+
+function part2(inp: number[][][]): number {
+  return inp
+    .filter(([before, after]) => before.join(',') !== after.join(','))
+    .reduce((t, [_, after]) => t + after[Math.floor(after.length / 2)], 0);
+}
+
+export default async function main(args: MainArgs): Promise<[number, number]> {
+  const inp = await parseFile<Parsed>(args);
+  const order = new Set<string>();
+  for (const [x, y] of inp[0]) {
+    order.add(`${x},${y}`);
+  }
+  const beforeAndAfter = inp[1].map((pages) => {
+    const sorted = [...pages].sort((a, b) => {
+      if (order.has(`${a},${b}`)) {
+        return -1;
+      }
+      if (order.has(`${b},${a}`)) {
+        return 1;
+      }
+      return 0;
+    });
+    return [pages, sorted];
+  });
+  return [part1(beforeAndAfter), part2(beforeAndAfter)];
+}

test/day5.js

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+export default [4662, 5900];