refactor

Author: shahata

src/2024/day12.js

@@ -1,19 +1,7 @@
-function countSides(walls) {
-  let sides = 0;
-  walls.forEach(cells => {
-    const points = [...cells].sort((a, b) => a - b);
-    for (let i = 0; i < points.length; i++) {
-      if (points[i] + 1 !== points[i + 1]) sides++;
-    }
-  });
-  return sides;
-}
-
 function walk(map, x, y) {
   const queue = [{ x, y }];
   const cells = new Set([`${x},${y}`]);
   const walls = new Map();
-  let perimeter = 0;
   while (queue.length > 0) {
     const p = queue.shift();
     const neighbors = [
@@ -29,7 +17,6 @@ function walk(map, x, y) {
           queue.push(o);
         }
       } else {
-        perimeter++;
         if (o.x === p.x) {
           const wall = `h,${p.y},${o.y}`;
           walls.set(wall, (walls.get(wall) || new Set()).add(p.x));
@@ -40,25 +27,46 @@ function walk(map, x, y) {
       }
     });
   }
-  return { cells, perimeter, sides: countSides(walls) };
+  return { cells, walls };
 }
 
-export function part1(input, part2 = false) {
+function forEachRegion(input, fn) {
   const map = input.split("\n").map(line => line.split(""));
   let visited = new Set();
-  let sum = 0;
   for (let y = 0; y < map.length; y++) {
     for (let x = 0; x < map[y].length; x++) {
       if (visited.has(`${x},${y}`)) continue;
-      const { cells, perimeter, sides } = walk(map, x, y);
+      const { cells, walls } = walk(map, x, y);
       visited = visited.union(cells);
-      if (!part2) sum += cells.size * perimeter;
-      else sum += cells.size * sides;
+      fn(cells, walls);
     }
   }
+}
+
+function countSides(walls) {
+  let sides = 0;
+  walls.forEach(cells => {
+    const points = [...cells].sort((a, b) => a - b);
+    for (let i = 0; i < points.length; i++) {
+      if (points[i] + 1 !== points[i + 1]) sides++;
+    }
+  });
+  return sides;
+}
+
+export function part1(input) {
+  let sum = 0;
+  forEachRegion(input, (cells, walls) => {
+    let perimeter = walls.values().reduce((acc, set) => acc + set.size, 0);
+    sum += cells.size * perimeter;
+  });
   return sum;
 }
 
 export function part2(input) {
-  return part1(input, true);
+  let sum = 0;
+  forEachRegion(input, (cells, walls) => {
+    sum += cells.size * countSides(walls);
+  });
+  return sum;
 }