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day18.js
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day18.js
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class Tile {
constructor(x, y, id) {
this.x = x;
this.y = y;
this.id = id;
this.visited = false;
}
toString() {
return "(x: " + this.x + ", y: " + this.y + ")";
}
}
var fs = require("fs");
let input = fs.readFileSync(__dirname +"/input.txt").toString().split("\n").filter(x => x);
let data = [];
let startX = 0, startY = 0, endX = 0, endY = 0, savedX, savedY;
let pos = new Tile(); pos.id = 1;
let keySymbols = [];
function print() {
for (let y = startY; y <= endY; y++) {
let line = "";
for (let x = startX; x <= endX; x++) {
let a = get(x, y);
if (x == pos.x && y == pos.y) line += "@";
else line += a.id;
}
console.log(line);
}
}
function add(x, y, id) {
if (id == "@") { pos.x = savedX = x; pos.y = savedY = y; id = "." };
for (let i = 0; i < data.length; i++) {
if (data[i].x == x && data[i].y == y) {
data[i].id = id;
data[i].visited = false;
return;
}
}
let t = new Tile(x, y, id);
data.push(t);
if (startX > x) startX = x;
if (startY > y) startY = y;
if (endX < x) endX = x;
if (endY < y) endY = y;
if (id != "." && id != "#" && id.toLowerCase() == id && keySymbols.indexOf(id) == -1) {
keySymbols.push(id);
}
}
function get(x, y) {
for (let i = 0; i < data.length; i++) {
if (data[i].x == x && data[i].y == y) {
return data[i];
}
}
return null;
}
function reset() {
for (let i = 0; i < data.length; i++) {
data[i].visited = false;
}
}
function nextPos(pos, dir) {
switch (dir) {
case 1: return new Tile(pos.x, pos.y - 1, dir);
case 2: return new Tile(pos.x + 1, pos.y, dir);
case 3: return new Tile(pos.x, pos.y + 1, dir);
case 4: return new Tile(pos.x - 1, pos.y, dir);
}
}
function canGo(tile, ignoreDoors) {
for (let i = 0; i < data.length; i++) {
if (data[i].x == tile.x && data[i].y == tile.y && data[i].visited) return false;
}
if (tile.id == ".") return true;
if (tile.id == "#") return false;
if (tile.id.toLowerCase() == tile.id) return true;
if (tile.id.toUpperCase() == tile.id)
if (ignoreDoors == false || ignoreDoors == undefined)
return false;
else
return true;
}
let save = true;
function nextMove(history, ignoreDoors) {
let dir = 0;
let nP;
do {
dir++;
nP = nextPos(pos, dir);
if (dir > 4) {
let last = history.pop();
if (last == undefined) return -1;
save = false;
switch (last.id) {
case 1: return 3;
case 2: return 4;
case 3: return 1;
case 4: return 2;
}
break;
}
} while (!canGo(get(nP.x, nP.y), ignoreDoors));
return dir;
}
function getSteps(destX, destY, ignoreDoors) {
let history = [];
let availableKeys = [];
let doorsVisited = [];
while (true) {
get(pos.x, pos.y).visited = true;
save = true;
let dir = nextMove(history, (destY == 0 && destX == 0) || ignoreDoors);
if (dir == -1) return availableKeys;
nP = nextPos(pos, dir);
let tile = get(nP.x, nP.y);
tile.visited = true;
if (save) {
pos.id = dir;
history.push(pos);
}
if (tile.id != "." && tile.id != "#" && tile.id.toLowerCase() == tile.id) {
if (destY == 0 && destX == 0) {
let f = availableKeys.find(x => { return x[0] == tile.id; } );
if (f == undefined) availableKeys.push([tile.id, history.length, [...doorsVisited]]);
else if (f[1] < history.length) { f[1] = history.length; f[2] = [...doorsVisited];}
} else if (!ignoreDoors) {
for (let i = 0; i < data.length; i++) {
if (data[i].id.toLowerCase() == tile.id && data[i] != tile) {
data[i].id = ".";
}
data[i].visited = false;
}
tile.id = ".";
pos = nP;
return history.length + getSteps(destX, destY);
}
} else if (tile.id != "." && tile.id != "#" && tile.id.toUpperCase() == tile.id) {
if (doorsVisited.indexOf(tile.id) == -1) doorsVisited.push(tile.id);
else doorsVisited.splice(doorsVisited.indexOf(tile.id), 1);
}
if (nP.x == destX && nP.y == destY) {
return history.length;
}
pos = nP;
/*print();
console.log(history.length);*/
}
}
function isReachable(required, collected) {
if (required.length == 0) return true;
if (collected.length < required.length) return false;
for (let i = 0; i < required.length; i++) {
if (collected.indexOf(required[i].toLowerCase()) == -1) return false;
}
return true;
}
function isSubset(a, b) {
for (let i = 0; i < a.length; i++) {
if (b.indexOf(a[i]) == -1) return false;
}
return true;
}
function findKey(sym) {
for (let i = 0; i < data.length; i++) {
if (data[i].id == sym)
return data[i];
}
}
for (let i = 0; i < input.length; i++) {
for (let j = 0; j < input[i].length; j++) {
add(j, i, input[i].charAt(j));
}
}
distances = [];
console.log("start distance between keys calculation");
for (let i = 0; i < keySymbols.length; i++) {
for (let j = i + 1; j < keySymbols.length; j++) {
let start = findKey(keySymbols[i]), end = findKey(keySymbols[j]);
reset();
pos.x = start.x;
pos.y = start.y;
distances.push([keySymbols[i]+" "+keySymbols[j], getSteps(end.x, end.y, true)]);
}
let end = findKey(keySymbols[i]);
reset();
pos.x = savedX;
pos.y = savedY;
distances.push([keySymbols[i]+" start", getSteps(end.x, end.y, true)]);
console.log(keySymbols[i] + " (" + i + "/" + keySymbols.length + ") done");
}
console.log("end distance between keys calculation");
let min = Number.MAX_SAFE_INTEGER;
function findPaths(history, remaining) {
if (remaining.length == 0) {
let sum = distances.find(x => { return x[0] == history[0] + " start"; })[1];
for (let i = 0; i < history.length - 1; i++) {
sum += distances.find(x => { return x[0] == history[i] + " " + history[i + 1] || x[0] == history[i + 1] + " " + history[i]; })[1];
}
if (sum < min) {
console.log(history.join(" ") + " " + sum);
min = sum;
}
}
for (let i = 0; i < remaining.length; i++) {
if (isReachable(remaining[i][2], history) && (i == 0 || !isSubset(remaining[i - 1][2], remaining[i][2]))) {
let newInv = [...history, remaining[i][0]];
findPaths(newInv, [...remaining.slice(0, i), ...remaining.slice(i + 1, remaining.length)]);
}
}
}
pos.x = savedX;
pos.y = savedY;
reset();
findPaths([], getSteps(0, 0));