aoc/2020/17/part1.js

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2020-12-17 21:21:20 +00:00
const fs = require('fs');
const textIn = fs.readFileSync('./input.txt', 'utf-8');
const iterAmt = 6;
// make a list of points to add at first
let startPoints = []
// could do forEach() instead of map() but i already did it like this and it works
startGrid = textIn.split('\n').map((line, y) => line.split('').map((point, x) => {
if (point=='#') {
startPoints.push([iterAmt+x,iterAmt+y,iterAmt])
}
return point=='#'
}));
// start with zero active cubes
let runningTotal = 0;
// create an empty pocket dimension
let p = new Pocket()
// add the points from the input
startPoints.forEach(point => add(...point, p));
for (let i = 0; i < iterAmt; i++) {
printLayer(p,iterAmt);
// create a deep copy of the current state
let next = p.map(layer => layer.map(row => row.map(cube => {return{active:cube.active,nearby:cube.nearby}})))
// for every single cube in the pocket dimension
p.forEach((layer, z) => layer.forEach((row, y) => row.forEach((cube, x) => {
// apply the game of life rules using p and store in next
if (cube.active && (cube.nearby < 2 || cube.nearby > 3)) {
remove(x,y,z,p,next)
} else if (!cube.active && (cube.nearby == 3)) {
add(x,y,z,p,next)
}
})))
p = next;
}
console.log(runningTotal);
// -------------------------------
function printLayer(pocket, layer) {
console.log( pocket[layer].reduce((a,b)=>a+b.reduce((c,d)=>c+(d.active?'\x1b[36m':'\x1b[0m')+(d.nearby.toString().length==1?'0':'')+d.nearby,'')+'\n',''))
}
// returns empty pocket dimension
function Pocket () {
let pocket = [];
for (let z = 0; z < iterAmt*2+1; z++) {
let layer = []
for (let y = 0; y < iterAmt*2+startGrid.length; y++) {
let row = []
row = Array(iterAmt*2 + startGrid[0].length).fill(0).map(()=>{return{active:false,nearby:0}})
layer.push(row)
}
pocket.push(layer)
}
return pocket
}
function add (x,y,z,before,after=before) {
if (before[z][y][x].active) return before; // if it's already active, do nothing
runningTotal++;
after[z][y][x].active = true;
// for every cube near the one we just added
for (let layer = Math.max(z-1, 0); layer <= Math.min(z+1, before.length-1); layer++) {
for (let row = Math.max(y-1, 0); row <= Math.min(y+1, before[0].length-1); row++) {
for (let col = Math.max(x-1, 0); col <= Math.min(x+1, before[0][0].length-1); col++) {
// but not the one we just added
if (layer == z && row == y && col == x) continue;
// there now is one more nearby cube
after[layer][row][col].nearby++
}
}
}
return after;
}
// add and remove could be combined into one function but i did it like this and it works
function remove (x,y,z,before,after=before) {
if (!before[z][y][x].active) return before;
runningTotal--;
after[z][y][x].active = false;
for (let layer = Math.max(z-1, 0); layer <= Math.min(z+1, before.length-1); layer++) {
for (let row = Math.max(y-1, 0); row <= Math.min(y+1, before[0].length-1); row++) {
for (let col = Math.max(x-1, 0); col <= Math.min(x+1, before[0][0].length-1); col++) {
if (layer == z && row == y && col == x) continue;
after[layer][row][col].nearby--
}
}
}
return after;
}