main
Yanick Champoux 2022-12-08 16:19:44 -05:00
parent 258a8f9795
commit 7fe01fdb57
4 changed files with 79 additions and 30 deletions

View File

@ -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;
}

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@ -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)
);

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@ -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.

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@ -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);
});
});