private static int FindLoopLength(int[] positions)
{
var velocity = new int[positions.Length];
var originalPositions = positions.ToArray();
var stepsCount = 0;
var finish = false;
while (!finish)
{
stepsCount++;
Moon.ApplyGravity(positions, velocity);
Moon.ApplyVelocity(positions, velocity);
finish = true;
for (var i = 0; i < positions.Length; i++)
{
if (positions[i] != originalPositions[i] || velocity[i] != 0)
{
finish = false;
break;
}
}
}
return(stepsCount);
}
public static long Solve(IEnumerable <string> input, int stepsCount = 1000)
{
var moons = input.Select(Moon.Parse).ToArray();
var positionX = moons.Select(i => i.X).ToArray();
var positionY = moons.Select(i => i.Y).ToArray();
var positionZ = moons.Select(i => i.Z).ToArray();
var velocityX = new int[moons.Length];
var velocityY = new int[moons.Length];
var velocityZ = new int[moons.Length];
for (var i = 0; i < stepsCount; i++)
{
Moon.ApplyGravity(positionX, velocityX);
Moon.ApplyGravity(positionY, velocityY);
Moon.ApplyGravity(positionZ, velocityZ);
Moon.ApplyVelocity(positionX, velocityX);
Moon.ApplyVelocity(positionY, velocityY);
Moon.ApplyVelocity(positionZ, velocityZ);
}
var result = 0L;
for (var i = 0; i < positionX.Length; i++)
{
long potential = Math.Abs(positionX[i]) + Math.Abs(positionY[i]) + Math.Abs(positionZ[i]);
long kinetic = Math.Abs(velocityX[i]) + Math.Abs(velocityY[i]) + Math.Abs(velocityZ[i]);
result += (potential * kinetic);
}
return(result);
}
