public async ValueTask <long> GetPart2()
{
// Setup moons in first position with 0 velocity
var moons = initialPositions.Select(x => new Moon()
{
Position = x
}).ToArray();
var xes = initialPositions.Select(p => p.x).ToArray();
var yes = initialPositions.Select(p => p.y).ToArray();
var zes = initialPositions.Select(p => p.z).ToArray();
var linked = new MoonWithInfluencingBodies[moons.Length];
for (var i = 0; i < moons.Length; i++)
{
var related = new List <Moon>(moons);
related.Remove(moons[i]);
linked[i] = new(moons[i], related.ToArray());
}
// Iterate system until all axes have reset at least once
long equalX = 0, equalY = 0, equalZ = 0, round = 0;
while (equalX == 0 || equalY == 0 || equalZ == 0)
{
MoveOneStep(linked);
round++;
if (equalX == 0 && moons.Select(m => m.Position.x).SequenceEqual(xes) && moons.All(m => m.Velocity.x == 0))
{
equalX = round;
}
if (equalY == 0 && moons.Select(m => m.Position.y).SequenceEqual(yes) && moons.All(m => m.Velocity.y == 0))
{
equalY = round;
}
if (equalZ == 0 && moons.Select(m => m.Position.z).SequenceEqual(zes) && moons.All(m => m.Velocity.z == 0))
{
equalZ = round;
}
}
// then find the first iteration where all 3 are reset
var sorted = new long[] { equalX, equalY, equalZ }.OrderByDescending(x => x).ToList();
return(LeastCommonMultiple(LeastCommonMultiple(sorted[0], sorted[1]), sorted[2]));
}
public async ValueTask <long> GetPart1()
{
// Setup moons in first position with 0 velocity
var moons = initialPositions.Select(x => new Moon()
{
Position = x
}).ToArray();
var linked = new MoonWithInfluencingBodies[moons.Length];
for (var i = 0; i < moons.Length; i++)
{
var related = new List <Moon>(moons);
related.Remove(moons[i]);
linked[i] = new(moons[i], related.ToArray());
}
for (var i = 1; i <= 1_000; i++)
{
MoveOneStep(linked);
}
return(moons.Sum(x => x.GetEnergy()));
}