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 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),
    }) )
    );

    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( 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");

function printMap( forest ) {
    forest.forEach( line => console.log(line.join(' ')) );
    return forest;
}

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