public Day12()
{
io = new Moon(5, -1, 5);
europa = new Moon(0, -14, 2);
ganymede = new Moon(16, 4, 0);
callisto = new Moon(18, 1, 16);
}
void ApplyGravity(Moon moon1, Moon moon2)
{
if (moon1.PositionX < moon2.PositionX)
{
moon1.VelocityX++;
moon2.VelocityX--;
}
else if (moon1.PositionX > moon2.PositionX)
{
moon1.VelocityX--;
moon2.VelocityX++;
}
if (moon1.PositionY < moon2.PositionY)
{
moon1.VelocityY++;
moon2.VelocityY--;
}
else if (moon1.PositionY > moon2.PositionY)
{
moon1.VelocityY--;
moon2.VelocityY++;
}
if (moon1.PositionZ < moon2.PositionZ)
{
moon1.VelocityZ++;
moon2.VelocityZ--;
}
else if (moon1.PositionZ > moon2.PositionZ)
{
moon1.VelocityZ--;
moon2.VelocityZ++;
}
}
int GetEnergy(Moon moon)
{
int pot = Math.Abs(moon.PositionX) + Math.Abs(moon.PositionY) + Math.Abs(moon.PositionZ);
int kin = Math.Abs(moon.VelocityX) + Math.Abs(moon.VelocityY) + Math.Abs(moon.VelocityZ);
return(pot * kin);
}
public long Part2()
{
io = new Moon(5, -1, 5);
europa = new Moon(0, -14, 2);
ganymede = new Moon(16, 4, 0);
callisto = new Moon(18, 1, 16);
Moon ioInitial = new Moon(5, -1, 5);
Moon europaInitial = new Moon(0, -14, 2);
Moon ganymedeInitial = new Moon(16, 4, 0);
Moon callistoInitial = new Moon(18, 1, 16);
int time = 1;
List <long> xCycles = new List <long>();
List <long> yCycles = new List <long>();
List <long> zCycles = new List <long>();
while (!xCycles.Any() || !yCycles.Any() || !zCycles.Any())
{
// apply gravity
ApplyGravity(io, europa);
ApplyGravity(io, ganymede);
ApplyGravity(io, callisto);
ApplyGravity(europa, ganymede);
ApplyGravity(europa, callisto);
ApplyGravity(ganymede, callisto);
ApplyVelocity(io);
ApplyVelocity(europa);
ApplyVelocity(ganymede);
ApplyVelocity(callisto);
time++;
if (ioInitial.PositionX == io.PositionX &&
europaInitial.PositionX == europa.PositionX &&
ganymedeInitial.PositionX == ganymede.PositionX &&
callistoInitial.PositionX == callisto.PositionX &&
ioInitial.VelocityX == io.VelocityX &&
europaInitial.VelocityX == europa.VelocityX &&
ganymedeInitial.VelocityX == ganymede.VelocityX &&
callistoInitial.VelocityX == callisto.VelocityX)
{
Console.WriteLine("X cycle at {0}", time);
xCycles.Add(time - 1);
}
if (ioInitial.PositionY == io.PositionY &&
europaInitial.PositionY == europa.PositionY &&
ganymedeInitial.PositionY == ganymede.PositionY &&
callistoInitial.PositionY == callisto.PositionY &&
ioInitial.VelocityY == io.VelocityY &&
europaInitial.VelocityY == europa.VelocityY &&
ganymedeInitial.VelocityY == ganymede.VelocityY &&
callistoInitial.VelocityY == callisto.VelocityY)
{
Console.WriteLine("Y cycle at {0}", time);
yCycles.Add(time - 1);
}
if (ioInitial.PositionZ == io.PositionZ &&
europaInitial.PositionZ == europa.PositionZ &&
ganymedeInitial.PositionZ == ganymede.PositionZ &&
callistoInitial.PositionZ == callisto.PositionZ &&
ioInitial.VelocityZ == io.VelocityZ &&
europaInitial.VelocityZ == europa.VelocityZ &&
ganymedeInitial.VelocityZ == ganymede.VelocityZ &&
callistoInitial.VelocityZ == callisto.VelocityZ)
{
Console.WriteLine("Z cycle at {0}", time);
zCycles.Add(time - 1);
}
}
return(MathUtils.Lcm(MathUtils.Lcm(xCycles.Min(), yCycles.Min()), zCycles.Min()));
}
void ApplyVelocity(Moon moon)
{
moon.PositionX += moon.VelocityX;
moon.PositionY += moon.VelocityY;
moon.PositionZ += moon.VelocityZ;
}
void PrintState(Moon moon)
{
Console.WriteLine("pos=<x= {0}, y= {1}, z= {2}>, vel=<x= {3}, y= {4}, z= {5}>",
moon.PositionX, moon.PositionY, moon.PositionZ,
moon.VelocityX, moon.VelocityY, moon.VelocityZ);
}