95 lines
2.3 KiB
JavaScript
95 lines
2.3 KiB
JavaScript
import * as R from "remeda";
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import Victor from "@a-robu/victor";
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import { readFile } from "../05/part1.js";
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const V = (x,y) => new Victor(x,y);
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const readInput = (...args) =>
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R.pipe(
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readFile(...args),
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(lines) => lines.split("\n"),
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R.compact, // remove last line
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R.map((line) => line.split("").map( c => c ==='S' ? '`' : c === 'E' ? '{' : c ))
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);
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export const puzzleInput = readInput(import.meta.url, "input");
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export const sample = readInput(import.meta.url, "sample");
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export const findStart = (topoMap) => {
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let y;
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let x = R.findIndex(topoMap, (row) => {
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let z = row.indexOf("`");
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if (z === -1) return false;
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y = z;
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return true;
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});
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return V(x,y);
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};
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const directions = [ [0,1], [0,-1],[1,0],[-1,0] ].map(
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d => V(...d)
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);
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const outOfMap = (maxX,maxY) => (loc) => {
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if( Math.min( loc.x, loc.y ) < 0 ) return true;
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if( loc.x >= maxX ) return true;
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if( loc.y >= maxY ) return true;
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return false;
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}
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const isReachable = (topoMap,pos) => {
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const baseline = topoMap[pos.x][pos.y].charCodeAt(0);
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return (next) => {
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return [0,1].includes(
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topoMap[next.x][next.y].charCodeAt(0) - baseline
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)
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}
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}
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function findShortestPath(topoMap) {
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const initial = findStart(topoMap);
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initial.steps = 0;
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initial.beenThere = [];
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const potentials = [ initial ];
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let bestSoFar;
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const oom = outOfMap(topoMap.length,topoMap[0].length );
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let failsafe = 100000;
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while( potentials.length > 0 ) {
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// if(! failsafe--) return;
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const pos = potentials.pop(); // depth-first
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//console.log(pos.steps, bestSoFar);
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if( bestSoFar && (bestSoFar <= pos.steps) ) continue;
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if( topoMap[pos.x][pos.y] === '{' ) {
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bestSoFar = pos.steps;
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continue;
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}
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const next = directions.map(
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d => d.clone().add(pos)
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).filter( R.isNot(oom ))
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.filter( isReachable(topoMap,pos) )
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.filter( next => !pos.beenThere.includes( next.toArray().join(',') ) );
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next.forEach( n => n.steps = pos.steps + 1 );
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next.forEach( n => n.beenThere = [
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...pos.beenThere, pos.toArray().join(',')
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] );
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potentials.push(...next);
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}
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return bestSoFar;
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}
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export default findShortestPath;
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