refactor(2025/day/10): separate masks from parsing

Author: mfulton26

2025/day/10/manuals.ts

@@ -0,0 +1,10 @@
+export function parseManual(text: string) {
+  return text.split("\n").map((line) => {
+    const [lightsText, ...rest] = line.split(" ");
+    const lights = lightsText.slice(1, -1);
+    const buttons = rest.slice(0, -1)
+      .map((text) => text.slice(1, -1).split(",").map(Number));
+    const requirements = rest.at(-1)!.slice(1, -1).split(",").map(Number);
+    return { lights, buttons, requirements };
+  });
+}

2025/day/10/part/1/solve.ts

@@ -1,31 +1,23 @@
 import subsets from "@lib/subsets.ts";
+import { parseManual } from "../../manuals.ts";
 
 export default function solve(input: string) {
-  const lines = input.split("\n").map((line) => {
-    const [lightsText, ...rest] = line.split(" ");
-    const lights = +`0b${
-      Array.from(lightsText.slice(1, -1), (c) => (c === "#" ? "1" : "0"))
-        .reverse().join("")
-    }`;
-    const buttons = rest.slice(0, -1)
-      .map((text) =>
-        text.slice(1, -1).split(",").map(Number)
-          .reduce((sum, n) => sum + 2 ** n, 0)
-      );
-    const requirements = rest.at(-1)!.slice(1, -1).split(",").map(Number);
-    return { lights, buttons, requirements };
-  });
+  const manual = parseManual(input);
   let sum = 0;
-  for (const { lights, buttons } of lines) {
-    let min = Infinity;
-    for (const presses of subsets(new Set(buttons))) {
-      if (presses.size >= min) continue;
-      let actual = 0;
-      for (const press of presses) actual ^= press;
-      if (actual !== lights) continue;
-      min = presses.size;
+  for (const { lights, buttons } of manual) {
+    const lightsMask = Array.from(lights, (c, i) => (c === "#" ? 1 << i : 0))
+      .reduce((mask, bit) => mask | bit, 0);
+    const buttonMasks = buttons.map((indices) =>
+      indices.reduce((mask, i) => mask | (1 << i), 0)
+    );
+    let minPresses = Infinity;
+    for (const presses of subsets(new Set(buttonMasks))) {
+      if (presses.size >= minPresses) continue;
+      let pressMask = 0;
+      for (const mask of presses) pressMask ^= mask;
+      if (pressMask === lightsMask) minPresses = presses.size;
     }
-    sum += min;
+    sum += minPresses;
   }
   return sum;
 }