2024/11/solution.nix

@@ -3,8 +3,6 @@
   inherit (lib.strings) toIntBase10;
 in input: rec {
 
-  sum = foldl' add 0;
-
   blinkStone = stone: count:
     if toIntBase10 stone == 0 then [{ "1" = count; }]
     else let
@@ -23,17 +21,19 @@ in input: rec {
   ;
 
   bfast = stones: stones
-    |> builtins.mapAttrs blinkStone
+    |> (builtins.mapAttrs (stone: blinkStone stone))
     |> attrValues
     |> concatLists
-    |> builtins.zipAttrsWith (stone: sum)
+    |> addStones
   ;
 
   bfastt = times: stones:
-    if times == 0 then stones |> attrValues |> sum
+    if times == 0 then stones |> attrValues |> foldl' add 0
     else bfastt (times - 1) (bfast stones)
   ;
 
+  addStones = builtins.zipAttrsWith (stone: foldl' add 0);
+
   initialStones = input
     |> lib.trim
     |> lib.splitString " "

2024/12/example.txt

@@ -1,4 +0,0 @@
-AAAA
-BBCD
-BBCC
-EEEC

2024/12/example2.txt

@@ -1,5 +0,0 @@
-OOOOO
-OXOXO
-OOOOO
-OXOXO
-OOOOO

2024/12/example3.txt

@@ -1,10 +0,0 @@
-RRRRIICCFF
-RRRRIICCCF
-VVRRRCCFFF
-VVRCCCJFFF
-VVVVCJJCFE
-VVIVCCJJEE
-VVIIICJJEE
-MIIIIIJJEE
-MIIISIJEEE
-MMMISSJEEE

2024/12/example4.txt

@@ -1,5 +0,0 @@
-EEEEE
-EXXXX
-EEEEE
-EXXXX
-EEEEE

2024/12/example5.txt

@@ -1,6 +0,0 @@
-AAAAAA
-AAABBA
-AAABBA
-ABBAAA
-ABBAAA
-AAAAAA

2024/12/solution.js

@@ -1,50 +0,0 @@
-
-const input = (await Bun.file(Bun.argv[2]).text()).trim()
-
-let map = input.split("\n")
-
-const dirs = [[-1,0], [1,0], [0, -1], [0, 1]];
-const height = map.length;
-const width = height;
-
-const key = (x,y) => x + y*width;
-const visited = new Set();
-
-function search(x,y) {
-  if (visited.has(key(x,y))) {
-    return {area: 0, perimeter: 0}
-  }
-  visited.add(key(x,y))
-  const letter = map[y][x]
-  let perimeter = 0
-  let area = 1
-  for (const [dx, dy] of dirs) {
-    const nletter = map[y + dy]?.[x + dx];
-    if (letter !== nletter) {
-      perimeter += 1
-      continue
-    }
-    const n = search(x + dx, y + dy)
-    area += n.area
-    perimeter += n.perimeter
-  }
-
-  return {area, perimeter}
-}
-
-const regions = [];
-
-for (let y = 0; y < height; y++) {
-  for (let x = 0; x < width; x++) {
-    if (visited.has(key(x,y))) continue
-    regions.push(search(x,y))
-  }
-}
-
-let cost = 0
-for (const {area, perimeter} of regions) {
-  cost += area * perimeter
-}
-console.log(cost)
-
-

2024/12/solution2.js

@@ -1,63 +0,0 @@
-
-const input = (await Bun.file(Bun.argv[2]).text()).trim()
-
-let map = input.split("\n")
-
-const dirs = [[-1,0], [0,-1], [1,0], [0, 1]];
-const height = map.length;
-const width = height;
-
-const key = (x,y) => x + y*width;
-const vkey = (x,y) => y + x*height;
-const visited = new Set();
-
-function search(x,y) {
-  if (visited.has(key(x,y))) {
-    return {area: 0, hsides: new Set()}
-  }
-  visited.add(key(x,y))
-  const letter = map[y][x]
-  let area = 1
-  let hsides = new Set()
-  for (const [dx, dy] of dirs) {
-    const nletter = map[y + dy]?.[x + dx];
-    if (letter !== nletter) {
-      if (dx === 0) {
-        hsides.add({y: y+dy/2, key: key(x,y)})
-      }
-      continue
-    }
-    const n = search(x + dx, y + dy)
-    area += n.area
-    hsides = hsides.union(n.hsides)
-  }
-
-  return {area, hsides}
-}
-
-const regions = [];
-
-for (let y = 0; y < height; y++) {
-  for (let x = 0; x < width; x++) {
-    if (visited.has(key(x,y))) continue
-    regions.push(search(x,y))
-  }
-}
-
-
-let cost = 0;
-for (const {area, hsides} of regions) {
-  // hacky filter of all perimeter nodes to extract adjacent
-  const horizontal = Array.from(hsides)
-    .sort((a, b) => a.key - b.key)
-    .sort((a, b) => a.y - b.y)
-    .filter(({y, key}, i, a) => a[i-1]?.key + 1 !== key || a[i-1]?.y !== y)
-    .length
-
-  // there's always an equal amount of horizontal and vertical sides
-  cost += area * (horizontal * 2)
-}
-
-console.log(cost)
-
-