AoC2025: day 11 part 1

Author: martapanc

2024-2025/src/2025/day11/day11.test.ts

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+import {part1, part2} from "./day11";
+
+describe('2025 Day 11', () => {
+    test('Part 1', async () => {
+        expect(await part1('testInput1')).toEqual(5);
+        expect(await part1('input')).toEqual(497);
+    });
+
+    test('Part 2', async () => {
+        // expect(await part2('testInput1')).toEqual(31);
+        // expect(await part2('input')).toEqual(29379307);
+    });
+});

2024-2025/src/2025/day11/day11.ts

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+import path from "node:path";
+import {readInputLineByLine} from "@utils/io";
+
+export async function part1(inputFile: string) {
+    return await day11(inputFile, countPaths);
+}
+
+export async function part2(inputFile: string) {
+    return await day11(inputFile);
+}
+
+async function day11(inputFile: string, calcFn?: (graph: Map<string, string[]>) => number) {
+    const inputPath = path.join(__dirname, inputFile);
+    const lines = await readInputLineByLine(inputPath);
+    const graph = parseGraph(lines);
+    return calcFn?.(graph);
+}
+
+function countPaths(graph: Map<string, string[]>): number {
+    const memo = new Map<string, number>();
+    const visiting = new Set<string>();
+
+    const dfs = (node: string): number => {
+        if (node === "out") return 1;
+        const cached = memo.get(node);
+        if (cached !== undefined) return cached;
+        if (visiting.has(node)) {
+            return 0;
+        }
+        visiting.add(node);
+        const neighbors = graph.get(node) ?? [];
+        let total = 0;
+        for (const next of neighbors) {
+            total += dfs(next);
+        }
+        visiting.delete(node);
+        memo.set(node, total);
+        return total;
+    };
+
+    return dfs("you");
+}
+
+function parseGraph(lines: string[]): Map<string, string[]> {
+    const graph = new Map<string, string[]>();
+    for (const raw of lines) {
+        const line = raw.trim();
+        if (line.length === 0)
+            continue;
+        const [fromPart, toPart] = line.split(":");
+        const from = fromPart.trim();
+        if (!from)
+            continue;
+        const outputs = toPart?.trim()
+            ? toPart.trim().split(/\s+/)
+            : [];
+        graph.set(from, outputs);
+    }
+    return graph;
+}

2024-2025/src/2025/day11/testInput1

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+aaa: you hhh
+you: bbb ccc
+bbb: ddd eee
+ccc: ddd eee fff
+ddd: ggg
+eee: out
+fff: out
+ggg: out
+hhh: ccc fff iii
+iii: out