Day 9: Rope Bridge / Visnu Pitiyanuvath

Visnu Pitiyanuvath

Workspace

Public

Advent of Code 2022

Edited

Mar 3, 2023

2 forks

1 star

all = d3

.map(

run(

d3.range(0, 10).map(() => [0, 0]),

data

(d) => d

)

.flatMap((knots, t) => knots.map(([x, y], i) => ({ t, x, y, i })))

part2 = new Set(d3.map(run(d3.range(0, 10).map(() => [0, 0]), data), d => String(d[9]))).size

part1 = new Set(d3.map(run([[0, 0], [0, 0]], data), d => String(d[1]))).size

function* run(initial, src) {

let state = initial;

yield state;

for (const { dir, n } of steps(src))

for (let i = 0; i < n; i++) yield (state = step(state, dir));

}

step = (state, dir) => {

const next = state.map((p) => p.slice());

const [head] = next;

// move head

head[0] += dirs[dir][0];

head[1] += dirs[dir][1];

// fix knots

for (let i = 1; i < next.length; i++) {

const t = next[i];

const [hx, hy] = next[i - 1];

const [dx, dy] = [hx - t[0], hy - t[1]];

if (Math.abs(dx) === 2) {

t[0] += Math.sign(dx);

if (Math.abs(dy) >= 1) t[1] += Math.sign(dy);

} else if (Math.abs(dy) === 2) {

t[1] += Math.sign(dy);

if (Math.abs(dx) >= 1) t[0] += Math.sign(dx);

}

return next;

}

dirs = ({ R: [1, 0], L: [-1, 0], U: [0, 1], D: [0, -1] })

steps = (src) =>

src

.trim()

.split("\n")

.map((l) => {

const [dir, n] = l.split(" ");

return { dir, n: +n };

})

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