advent-of-code/2022/9/index2.js

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const fs = require('fs/promises');
const tailVisited = {'0~0': true};
const rope = [[0,0], [0,0], [0,0], [0,0], [0,0], [0,0], [0,0], [0,0], [0,0], [0,0]];
const keypress = async () => {
process.stdin.setRawMode(true)
return new Promise(resolve => process.stdin.once('data', data => {
const byteArray = [...data]
if (byteArray.length > 0 && byteArray[0] === 3) {
console.log('^C')
process.exit(1)
}
process.stdin.setRawMode(false)
resolve()
}))
}
const moveRope = (direction) => {
const lastSpot = [rope[0][0], rope[0][1]];
switch (direction) {
case "R":
rope[0][0] += 1;
break;
case "L":
rope[0][0] -= 1;
break;
case "U":
rope[0][1] -= 1;
break;
case "D":
rope[0][1] += 1;
break;
}
for(let i = 1; i < rope.length; ++i) {
rope[i] = moveSeg(rope[i], i)
}
}
const moveSeg = ([x, y], i) => {
if(i === rope.length) return;
const seg = rope[i - 1];
//console.log("uhh: ", rope, " ", i, " ", seg);
const [lx, ly] = seg;
V= rope[i - 1];
if(lx === x) {
if(ly === y + 2) {
return [x, y + 1];
}
if(ly === y - 2) {
return[x, y - 1];
}
}
if(ly === y) {
if(lx === x + 2) {
return [x + 1, y];
}
if(lx === x - 2) {
return rope[i] = [x - 1, y];
}
}
if(Math.max(Math.abs(x - lx), Math.abs(y - ly)) > 1) {
const xDiff = lx - x;
const yDiff = ly - y;
if(xDiff === 0 || yDiff === 0) {
console.log([x, y, lx, ly])
console.log("ROPE: ", rope);
}
return [x + xDiff/Math.abs(xDiff), y + yDiff/Math.abs(yDiff)];
}
return [x, y];
}
const printGraph = () => {
console.log("\n");
console.log(rope);
console.log("\n");
for(let y = -15; y <= 15; y++) {
const row = ["·", "·", "·", "·", "·",
"·", "·", "·", "·", "·",
"·", "·", "·", "·", "·",
"·", "·", "·", "·", "·",
"·", "·", "·", "·", "·",
"·", "·", "·", "·", "·", "·"].map((spot, i) => {
const x = i - 15;
const [hx, hy] = rope[0];
const [tx, ty] = rope[9];
let ch = "·";
if(!(y % 5) && !(x % 5)) {
ch = "▪";
}
if(y === 0 && x === 0) {
ch = "0";
}
if(y === ty && x === tx) {
ch = "T";
}
rope.slice(0, -1).reverse().forEach(([a, b], j) => {
if(a === x && b === y) {
ch = j+1;
}
});
if(y === hy && x === hx) {
ch = "H";
}
return ch;
});
console.log(row.join(""));
}
console.log("\n\n");
};
(async () => {
const input = await fs.readFile("./input.txt", 'utf8');
const lines = input.split("\n").map(t => t.split(" "));
//printGraph();
for (const [direction, times] of lines) {
for(let i = 0; i < times; ++i) {
//await keypress();
console.log("Moving ", direction);
moveRope(direction);
//printGraph();
tailVisited[`${rope[9][0]}~${rope[9][1]}`] = true;
}
}
console.log(tailVisited);
console.log(Object.values(tailVisited).length);
})();