Advent of Code: 2024 Day 8 / Jo Wood

Jo Wood

Professor of Visual Analytics interested in design, geovisualization, visual storytelling and computational thinking.

Workspace

Public

Ξ🎄Advent of Code 2024

Edited

Dec 8

Paused

function parse(input) {

const grid = input.split("\n").map((line) => line.split(""));

const nodes = grid.reduce((map, gRow, row) => {

gRow.forEach((type, col) => {

if (type !== ".") {

map.set(type, [...(map.get(type) || []), { row, col }]);

}

});

return map;

}, new Map());

return { nodes, nRows: grid.length, nCols: grid[0].length };

}

function findAntinodes(antennae, displacements = [2]) {

const antinodes = [];

const inBounds = ([r, c]) =>

r >= 0 && r < antennae.nRows && c >= 0 && c < antennae.nCols;

antennae.nodes.forEach((locations) => {

AOC.select(locations).forEach(([n, others]) => {

others.forEach((other) => {

const v = [other.row - n.row, other.col - n.col];

antinodes.push(

AOC.mapWhile(

(d) => [n.row + d * v[0], n.col + d * v[1]],

inBounds,

displacements

)

);

});

return antinodes.flat();

}

function part1(input) {

const nodes = parse(input);

const antinodes = findAntinodes(nodes);

return new Set(antinodes.map(([r, c]) => r * nodes.nCols + c)).size;

}

function part2(input) {

const nodes = parse(input);

const antinodes = findAntinodes(nodes, d3.range(1, nodes.nRows));

return new Set(antinodes.map(([r, c]) => r * nodes.nCols + c)).size;

}

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