adventofcode/2022/08/part1.js

import * as R from "remeda";
import { readFile } from "../05/part1.js";
import Victor from "@a-robu/victor";

const V = (...args) => new Victor(...args);

const readInput = (...args) =>
  readFile(...args)
    .split("\n")
    .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)
    .fill(null)
    .map(() => Array(size).fill(false));

  // top
  const positions = R.range(size)(0).map((x) => ({
    height: -1,
    position: V(x, -1),
    inc: V(0, 1),
  }));

  // bottom
  positions.push(
    ...R.range(size)(0).map((x) => ({
      height: -1,
      position: V(x, size),
      inc: V(0, -1),
    }))
  );

  positions.push(
    ...R.range(size)(0).map((x) => ({
      height: -1,
      position: V(-1, x),
      inc: V(1, 0),
    }))
  );
  positions.push(
    ...R.range(size)(0).map((x) => ({
      height: -1,
      position: V(size, x),
      inc: V(-1, 0),
    }))
  );

  while (positions.length) {
    const pos = positions.shift();
    pos.position.add(pos.inc);

    if (outOfBound(size)(pos.position)) continue;

    if (forest[pos.position.x][pos.position.y] > pos.height) {
      visibility[pos.position.x][pos.position.y] = true;
      pos.height = forest[pos.position.x][pos.position.y];
    }

    positions.push(pos);
  }

  return visibility;
}

export const puzzleInput = readInput(import.meta.url, "input");
export const sample = readInput(import.meta.url, "sample");

export const passthru = (func) => (arg) => {
  func(arg);
  return arg;
};

export const printMap = passthru((forest) =>
  forest.forEach((line) => console.log(line.join(" ")))
);

export default R.createPipe(
  generateVisibilityGrid,
  R.flatten,
  R.countBy(R.identity)
);