asteroids = {
// let's start by processing the positions of all asteroids into memory
const asteroids = new Map();
input.split('\n').forEach((row, y) => {
row.split('').forEach((point, x) => {
if (point === '#') {
asteroids.set({ x, y }, 0);
}
});
});
let best = 0;
const points = [...asteroids.keys()];
// for each point in our map, how many asteroids can it detect?
points.forEach((a) => {
const above = new Set();
const below = new Set();
points.forEach((b) => {
if (a === b) {
return;
}
const slope = (b.y - a.y) / (b.x - a.x);
if (b.y < a.y || (b.y === a.y && b.x < a.x)) {
if (above.has(slope)) {
return;
}
above.add(slope);
} else {
if (below.has(slope)) {
return;
}
below.add(slope);
}
asteroids.set(a, asteroids.get(a) + 1);
});
});
return asteroids;
}
[...asteroids.values()].sort((a, b) => a - b).pop();
{
const points = [...asteroids.keys()];
const station = points.reduce((a, b) => asteroids.get(a) > asteroids.get(b) ? a : b);
const toVaporize = points.filter(p => p !== station);
const sortDist = (a, b) => {
return (
Math.abs(station.x - a.x) +
Math.abs(station.y - a.y) -
(Math.abs(station.x - b.x) + Math.abs(station.y - b.y))
);
};
// for each asteroid to vaporize compute its angle relative to the station
const anglesToPoints = new Map();
toVaporize.forEach(point => {
const angle = (180 / Math.PI) * Math.atan2(point.x - station.x, point.y - station.y);
if (anglesToPoints.has(angle)) {
anglesToPoints.set(
angle,
anglesToPoints
.get(angle)
.concat([point])
.sort(sortDist)
);
} else {
anglesToPoints.set(angle, [point]);
}
});
const sortedAngles = [...anglesToPoints.keys()].sort((a, b) => a - b);
// NOTE this only works if there are asteroids already at an angle of 180
let i = sortedAngles.indexOf(180);
let destroyed = 0;
while (true) {
const angleOfAttack = sortedAngles[i];
const target = anglesToPoints.get(angleOfAttack).shift();
if (target) {
destroyed++;
}
if (destroyed === 200) {
return target.x * 100 + target.y;
}
i--;
if (i === -1) {
i = sortedAngles.length - 1;
}
}
}
Purpose-built for displays of data
Observable is your go-to platform for exploring data and creating expressive data visualizations. Use reactive JavaScript notebooks for prototyping and a collaborative canvas for visual data exploration and dashboard creation.
