AoC2025: day 10 part 1

Author: martapanc

2024-2025/setupDay.mjs

@@ -84,6 +84,10 @@ describe('${year} Day ${day}', () => {
         ws.write(content);
         ws.end();
 
+        const testInput1Path = path.join(`${dirName}/testInput1`);
+        fs.writeFileSync(testInput1Path, '');
+        console.log(`Empty testInput1 created!`);
+
         const inputPath = path.join(`${dirName}/input`);
 
         try {

2024-2025/src/2025/day10/day10.test.ts

@@ -0,0 +1,13 @@
+import {part1, part2} from "./day10";
+
+describe('2025 Day 10', () => {
+    test('Part 1', async () => {
+        expect(await part1('testInput1')).toEqual(7);
+        expect(await part1('input')).toEqual(428);
+    });
+
+    test('Part 2', async () => {
+        // expect(await part2('testInput1')).toEqual(31);
+        // expect(await part2('input')).toEqual(29379307);
+    });
+});

2024-2025/src/2025/day10/day10.ts

@@ -0,0 +1,103 @@
+import path from "node:path";
+import {readInputLineByLine} from "@utils/io";
+
+export async function part1(inputFile: string) {
+    return await day10(inputFile, calcButtonPresses);
+}
+
+export async function part2(inputFile: string) {
+    return await day10(inputFile);
+}
+
+async function day10(inputFile: string, calcFn?: (machines: Machine[]) => number) {
+    const inputPath = path.join(__dirname, inputFile);
+    const lines = await readInputLineByLine(inputPath);
+    const machines = lines.map(parseMachine);
+    return calcFn?.(machines);
+}
+
+type Machine = { target: bigint; buttons: bigint[]; };
+
+function parseMachine(line: string): Machine {
+    const diagramMatch = line.match(/\[([.#]+)\]/);
+    const diagram = diagramMatch![1];
+    let target = 0n;
+    for (let i = 0; i < diagram.length; i++) {
+        if (diagram[i] === '#') {
+            target |= 1n << BigInt(i);
+        }
+    }
+
+    const buttons: bigint[] = [];
+    const buttonMatches = line.matchAll(/\(([^)]+)\)/g);
+    for (const match of buttonMatches) {
+        const content = match[1].trim();
+        if (content.length === 0) continue;
+        let mask = 0n;
+        for (const part of content.split(',')) {
+            const idx = Number.parseInt(part.trim(), 10);
+            if (Number.isNaN(idx)) continue;
+            mask |= 1n << BigInt(idx);
+        }
+        buttons.push(mask);
+    }
+
+    return {target, buttons};
+}
+
+function calcButtonPresses(machines: Machine[]): number {
+    let total = 0;
+    machines.forEach((machine) => {
+        total += minButtonPresses(machine.target, machine.buttons);
+    });
+    return total;
+}
+
+function minButtonPresses(target: bigint, buttons: bigint[]): number {
+    if (target === 0n) return 0;
+    if (buttons.length === 0) return -1;
+
+    const mid = Math.floor(buttons.length / 2);
+    const left = buttons.slice(0, mid);
+    const right = buttons.slice(mid);
+
+    const leftMap = buildSubsetMinWeights(left);
+    let best = Number.POSITIVE_INFINITY;
+
+    const visitRight = (index: number, mask: bigint, weight: number) => {
+        if (index === right.length) {
+            const needed = target ^ mask;
+            const leftWeight = leftMap.get(needed);
+            if (leftWeight !== undefined) {
+                const total = leftWeight + weight;
+                if (total < best) best = total;
+            }
+            return;
+        }
+        visitRight(index + 1, mask, weight);
+        visitRight(index + 1, mask ^ right[index], weight + 1);
+    };
+
+    visitRight(0, 0n, 0);
+
+    return Number.isFinite(best) ? best : -1;
+}
+
+function buildSubsetMinWeights(buttons: bigint[]): Map<bigint, number> {
+    const map = new Map<bigint, number>();
+
+    const visit = (index: number, mask: bigint, weight: number) => {
+        if (index === buttons.length) {
+            const existing = map.get(mask);
+            if (existing === undefined || weight < existing) {
+                map.set(mask, weight);
+            }
+            return;
+        }
+        visit(index + 1, mask, weight);
+        visit(index + 1, mask ^ buttons[index], weight + 1);
+    };
+
+    visit(0, 0n, 0);
+    return map;
+}

2024-2025/src/2025/day10/testInput1

@@ -0,0 +1,3 @@
+[.##.] (3) (1,3) (2) (2,3) (0,2) (0,1) {3,5,4,7}
+[...#.] (0,2,3,4) (2,3) (0,4) (0,1,2) (1,2,3,4) {7,5,12,7,2}
+[.###.#] (0,1,2,3,4) (0,3,4) (0,1,2,4,5) (1,2) {10,11,11,5,10,5}