public string SolvePart1()
{
var orbitMap = new OrbitMap();
orbitMap.Build(Input);
return($"Part 1: {orbitMap.OrbitChecksum}");
}
public string SolvePart2()
{
var orbitMap = new OrbitMap();
orbitMap.Build(Input);
if (orbitMap.CenterOfMass == null)
{
throw new Exception("Something went wrong building the Orbit Map");
}
// 1. Find what you're orbiting
OrbitingObject?yourOrbit = FindOrbitingObject(orbitMap.CenterOfMass, "YOU");
// 2. Find what Santa's orbiting
OrbitingObject?santasOrbit = FindOrbitingObject(orbitMap.CenterOfMass, "SAN");
var visitedByYou = new Dictionary <string, int>();
var visitedBySanta = new Dictionary <string, int>();
string commonObjectName = string.Empty;
if (yourOrbit != null && santasOrbit != null)
{
// 3. Figure out how to get from whatever YOU are orbiting to whatever SAN is orbiting
OrbitingObject?path1 = yourOrbit;
visitedByYou.Add(path1.Name ?? "UNK", 0);
var yourJumpCount = 0;
OrbitingObject?path2 = santasOrbit;
visitedBySanta.Add(path2.Name ?? "UNK", 0);
var santasJumpCount = 0;
while (string.IsNullOrWhiteSpace(commonObjectName))
{
if (path1 != null && string.IsNullOrWhiteSpace(commonObjectName))
{
path1 = FindOrbitingObject(orbitMap.CenterOfMass, path1.Name ?? "UNK");
if (path1 != null)
{
yourJumpCount++;
visitedByYou.Add(path1.Name ?? "UNK", yourJumpCount);
// Exit condition
commonObjectName = path1.Name != null && visitedBySanta.ContainsKey(path1.Name) ? path1.Name : string.Empty;
}
}
if (path2 != null && string.IsNullOrWhiteSpace(commonObjectName))
{
path2 = FindOrbitingObject(orbitMap.CenterOfMass, path2.Name ?? "UNK");
if (path2 != null)
{
santasJumpCount++;
visitedBySanta.Add(path2.Name ?? "UNK", santasJumpCount);
// Exit condition
commonObjectName = path2.Name != null && visitedByYou.ContainsKey(path2.Name) ? path2.Name : string.Empty;
}
}
}
}
return(visitedByYou.ContainsKey(commonObjectName) && visitedBySanta.ContainsKey(commonObjectName)
? $"Part 2: {visitedByYou[commonObjectName] + visitedBySanta[commonObjectName]}"
: "Part 2: Unknown");
}