function parse(input) {
return input
.split("\n")
.map((s) => s.match(/(\w+ generator|\w+-compatible microchip)|(nothing)/g))
.map((items) => {
return [
items
.filter((item) => item.endsWith("generator"))
.map((item) => item.split(/[ |-]/)[0])
.map((item) => item.slice(0, 2) + "G"),
items
.filter((item) => item.endsWith("microchip"))
.map((item) => item.split(/[ |-]/)[0])
.map((item) => item.slice(0, 2) + "M")
].flat();
});
}
function atGoal(state) {
return state.slice(0, 3).flat().length === 0;
}
function getCombinations(items) {
const combinations = [];
for (let i = 0; i < items.length; i++) {
combinations.push([items[i]]);
for (let j = i + 1; j < items.length; j++) {
combinations.push([items[i], items[j]]);
}
}
return combinations;
}
function move(state, from, to, items) {
const newState = AOC.cloneArray(state);
for (const item of items) {
const index = newState[from].indexOf(item);
newState[from].splice(index, 1);
newState[to].push(item);
}
return newState;
}
function willFry(floor) {
const gens = floor
.filter((item) => item.endsWith("G"))
.map((g) => g.slice(0, -1));
if (gens.length === 0) {
return false; // Can't fry if no generators on this floor.
}
// Will fry if some microchip doesn't have a matching generator.
return floor
.filter((item) => item.endsWith("M"))
.some((chip) => !gens.includes(chip.slice(0, -1)));
}
function heuristic(state) {
let totalDistance = 0;
const k = 100; // A little larger than approximate shortest steps
for (let i = 0; i < 3; i++) {
totalDistance += state[i].length * (k - i);
}
return totalDistance;
}
function genericState(state) {
// Store a string of Gs and Ms representing number of generators and microchips on each floor
return state.map((floor) => floor.map((item) => item[2]).sort());
}
function minTransitions(state) {
const visited = new Set();
const queue = new PriorityQueue();
queue.put([state, 0, 0], 0);
while (!queue.isEmpty()) {
const [state, floor, nTransitions] = queue.get();
const gState = JSON.stringify([floor, genericState(state)]);
if (visited.has(gState)) {
continue; // We've been here before
}
visited.add(gState);
if (atGoal(state)) {
return nTransitions; // We've reached the top floor with all items!
}
const items = state[floor];
const payloads = getCombinations(items);
for (const payload of payloads) {
for (const direction of [-1, 1]) {
const newFloor = floor + direction;
if (newFloor < 0 || newFloor > 3) {
continue; // No floor to move to
}
const newState = move(state, floor, newFloor, payload);
if (willFry(newState[floor]) || willFry(newState[newFloor])) {
continue; // Invalid move
}
const priority = nTransitions + 1 + heuristic(newState);
queue.put([newState, newFloor, nTransitions + 1], priority);
}
}
}
return -1; // No more possible states and we haven't reached the goal.
}
function part2(input) {
const initState = parse(input);
initState[0] = initState[0].concat(["elG", "elM", "diG", "diM"]);
return minTransitions(initState);
}
One platform to build and deploy the best data apps
Experiment and prototype by building visualizations in live JavaScript notebooks. Collaborate with your team and decide which concepts to build out.
Use Observable Framework to build data apps locally. Use data loaders to build in any language or library, including Python, SQL, and R.
Seamlessly deploy to Observable. Test before you ship, use automatic deploy-on-commit, and ensure your projects are always up-to-date.