refactor

src/2024/day16.js

@@ -7,7 +7,7 @@ function parse(input) {
   return { map, start: { x, y, direction: "right" }, end: { x: ex, y: ey } };
 }
 
-function getNeighbors(current, map) {
+function getNeighbors(map, current) {
   const opposite = { up: "down", down: "up", left: "right", right: "left" };
   let neighbors = [
     { x: current.x - 1, y: current.y, direction: "left" },
@@ -25,22 +25,22 @@ function getNeighbors(current, map) {
   return neighbors;
 }
 
-function solve(input) {
+export function solve(input) {
+  const key = p => `${p.x},${p.y},${p.direction}`;
   let { map, start, end } = parse(input);
   let curr = { ...start, score: 0, path: new Set([`${start.x},${start.y}`]) };
   let queue = [curr];
-  let visited = new Map();
-  let results = [{ score: Infinity }];
-  const key = p => `${p.x},${p.y},${p.direction}`;
-  visited.set(key(curr), curr);
+  let visited = new Map([[key(curr), curr]]);
+  let score = Infinity;
+  let tiles;
   while (queue.length > 0) {
     curr = queue.shift();
     if (curr.x === end.x && curr.y === end.y) {
-      if (curr.score < results[0].score) results = [curr];
-      if (curr.score === results[0].score) results.push(curr);
+      if (curr.score < score) tiles = curr.path.size;
+      score = Math.min(score, curr.score);
       continue;
     }
-    getNeighbors(curr, map).forEach(n => {
+    getNeighbors(map, curr).forEach(n => {
       const prev = visited.get(key(n));
       if (!prev || prev.score > n.score) {
         queue.push(n);
@@ -50,14 +50,13 @@ function solve(input) {
       }
     });
   }
-  return results;
+  return { score, tiles };
 }
 
 export function part1(input) {
-  return solve(input)[0].score;
+  return solve(input).score;
 }
 
 export function part2(input) {
-  const results = solve(input).map(result => result.path);
-  return results.reduce((acc, next) => acc.union(next)).size;
+  return solve(input).tiles;
 }