prettier

2022/08/part1.js

@@ -10,6 +10,12 @@ const readInput = (...args) =>
     .filter((x) => x)
     .map((l) => l.split("").map((x) => parseInt(x)));
 
+export const outOfBound = (size) => (pos) => {
+  if (Math.min(pos.x, pos.y) < 0) return true;
+  if (Math.max(pos.x, pos.y) >= size) return true;
+  return false;
+};
+
 export function generateVisibilityGrid(forest) {
   const size = forest.length;
   const visibility = Array(size)
@@ -47,17 +53,11 @@ export function generateVisibilityGrid(forest) {
     }))
   );
 
-  const outOfBound = (pos) => {
-    if (Math.min(pos.x, pos.y) < 0) return true;
-    if (Math.max(pos.x, pos.y) >= size) return true;
-    return false;
-  };
-
   while (positions.length) {
     const pos = positions.shift();
     pos.position.add(pos.inc);
 
-    if (outOfBound(pos.position)) continue;
+    if (outOfBound(size)(pos.position)) continue;
 
     if (forest[pos.position.x][pos.position.y] > pos.height) {
       visibility[pos.position.x][pos.position.y] = true;
@@ -73,7 +73,7 @@ export function generateVisibilityGrid(forest) {
 export const puzzleInput = readInput(import.meta.url, "input");
 export const sample = readInput(import.meta.url, "sample");
 
-function printMap(forest) {
+export function printMap(forest) {
   forest.forEach((line) => console.log(line.join(" ")));
   return forest;
 }

2022/08/part2.js

@@ -1,4 +1,50 @@
 import * as R from "remeda";
+import memo from "memoizerific";
+import Victor from "@a-robu/victor";
 
+import { printMap, outOfBound } from "./part1";
 
-export default () => {};
+const V = (...args) => new Victor(...args);
+
+function visibility(forest, x, y, dx, dy) {
+  const pos = V(x, y);
+  const inc = V(dx, dy);
+
+  let vis = 0;
+
+  while (true) {
+    pos.add(inc);
+    if (outOfBound(forest.length)(pos)) return vis;
+
+    if (forest[x][y] <= forest[pos.x][pos.y]) return 1 + vis;
+    vis++;
+  }
+}
+
+const visibilityAround = (forest) => (x, y) => {
+  return [
+    [0, 1],
+    [0, -1],
+    [1, 0],
+    [-1, 0],
+  ]
+    .map((d) => visibility(forest, x, y, ...d))
+    .reduce((a, b) => a * b);
+};
+
+export default R.createPipe(
+  (forest) => {
+    const viz = Array(forest.length)
+      .fill(null)
+      .map(() => Array(forest.length).fill(0));
+
+    for (const x of R.range(0, forest.length)) {
+      for (const y of R.range(0, forest.length)) {
+        viz[x][y] = visibilityAround(forest)(x, y);
+      }
+    }
+    return viz;
+  },
+  R.flatten,
+  R.maxBy(R.identity)
+);

2022/08/puzzle.md

@@ -1,9 +1,8 @@
-\--- Day 8: Treetop Tree House ---
-----------
+## \--- Day 8: Treetop Tree House ---
 
 The expedition comes across a peculiar patch of tall trees all planted carefully in a grid. The Elves explain that a previous expedition planted these trees as a reforestation effort. Now, they're curious if this would be a good location for a [tree house](https://en.wikipedia.org/wiki/Tree_house).
 
-First, determine whether there is enough tree cover here to keep a tree house *hidden*. To do this, you need to count the number of trees that are *visible from outside the grid* when looking directly along a row or column.
+First, determine whether there is enough tree cover here to keep a tree house _hidden_. To do this, you need to count the number of trees that are _visible from outside the grid_ when looking directly along a row or column.
 
 The Elves have already launched a [quadcopter](https://en.wikipedia.org/wiki/Quadcopter) to generate a map with the height of each tree (your puzzle input). For example:
 
@@ -18,24 +17,24 @@ The Elves have already launched a [quadcopter](https://en.wikipedia.org/wiki/Qua
 
 Each tree is represented as a single digit whose value is its height, where `0` is the shortest and `9` is the tallest.
 
-A tree is *visible* if all of the other trees between it and an edge of the grid are *shorter* than it. Only consider trees in the same row or column; that is, only look up, down, left, or right from any given tree.
+A tree is _visible_ if all of the other trees between it and an edge of the grid are _shorter_ than it. Only consider trees in the same row or column; that is, only look up, down, left, or right from any given tree.
 
-All of the trees around the edge of the grid are *visible* - since they are already on the edge, there are no trees to block the view. In this example, that only leaves the *interior nine trees* to consider:
+All of the trees around the edge of the grid are _visible_ - since they are already on the edge, there are no trees to block the view. In this example, that only leaves the _interior nine trees_ to consider:
 
-* The top-left `5` is *visible* from the left and top. (It isn't visible from the right or bottom since other trees of height `5` are in the way.)
-* The top-middle `5` is *visible* from the top and right.
-* The top-right `1` is not visible from any direction; for it to be visible, there would need to only be trees of height *0* between it and an edge.
-* The left-middle `5` is *visible*, but only from the right.
-* The center `3` is not visible from any direction; for it to be visible, there would need to be only trees of at most height `2` between it and an edge.
-* The right-middle `3` is *visible* from the right.
-* In the bottom row, the middle `5` is *visible*, but the `3` and `4` are not.
+- The top-left `5` is _visible_ from the left and top. (It isn't visible from the right or bottom since other trees of height `5` are in the way.)
+- The top-middle `5` is _visible_ from the top and right.
+- The top-right `1` is not visible from any direction; for it to be visible, there would need to only be trees of height _0_ between it and an edge.
+- The left-middle `5` is _visible_, but only from the right.
+- The center `3` is not visible from any direction; for it to be visible, there would need to be only trees of at most height `2` between it and an edge.
+- The right-middle `3` is _visible_ from the right.
+- In the bottom row, the middle `5` is _visible_, but the `3` and `4` are not.
 
 With 16 trees visible on the edge and another 5 visible in the interior, a total of `*21*` trees are visible in this arrangement.
 
-Consider your map; *how many trees are visible from outside the grid?*
+Consider your map; _how many trees are visible from outside the grid?_
 
 To begin, [get your puzzle input](8/input).
 
 Answer:
 
-You can also [Shareon [Twitter](https://twitter.com/intent/tweet?text=%22Treetop+Tree+House%22+%2D+Day+8+%2D+Advent+of+Code+2022&url=https%3A%2F%2Fadventofcode%2Ecom%2F2022%2Fday%2F8&related=ericwastl&hashtags=AdventOfCode) [Mastodon](javascript:void(0);)] this puzzle.
+You can also [Shareon [Twitter](https://twitter.com/intent/tweet?text=%22Treetop+Tree+House%22+%2D+Day+8+%2D+Advent+of+Code+2022&url=https%3A%2F%2Fadventofcode%2Ecom%2F2022%2Fday%2F8&related=ericwastl&hashtags=AdventOfCode) [Mastodon](<javascript:void(0);>)] this puzzle.

2022/08/test.js

@@ -1,21 +1,25 @@
 import { test, expect, describe } from "vitest";
 
 import { expectSolution } from "../01/main.js";
-import part1, { sample, puzzleInput, generateVisibilityGrid } from "./part1.js";
+import part1, { sample, puzzleInput } from "./part1.js";
 import part2 from "./part2.js";
 
 describe("part 1", () => {
-    test( "sample", () => {
-        expect( part1(sample) ).toBe(21);
-
-    });
+  test("sample", () => {
+    expect(part1(sample)).toBe(21);
+  });
   test("solution", () => {
     expectSolution(part1(puzzleInput)).toEqual(1703);
   });
 });
 
 describe("part 2", () => {
-  test.todo("solution", () => {
-    expectSolution(part2(puzzleInput)).toEqual("TODO");
+  test("sample", () => {
+    expect(part2(sample)).toBe(8);
+  });
+  test("solution", () => {
+    const solution = part2(puzzleInput);
+    expect(solution).toBeGreaterThan(160);
+    expectSolution(solution).toEqual(496650);
   });
 });