public static long ManhattanDistance(Coordinate a, Coordinate b)
{
long res = Math.Abs(a.X - b.X) + Math.Abs(a.Y - b.Y) + Math.Abs(a.Z - b.Z);
return(res);
}
static void Main(string[] args)
{
var lines = File.ReadAllLines("./input.txt");
List <Coordinate> coords = new List <Coordinate>();
foreach (var line in lines)
{
var xyz = line.Split('>')[0].Split('<')[1].Split(',').Select(long.Parse).ToList();
var range = long.Parse(line.Split("r=")[1]);
var c = new Coordinate
{
Range = range,
X = xyz[0],
Y = xyz[1],
Z = xyz[2]
};
coords.Add(c);
}
//Part1
var largestRangeCoord = coords.Aggregate((x, y) => x.Range >= y.Range ? x : y);
int count = 0;
foreach (var coordinate in coords)
{
if (ManhattanDistance(coordinate, largestRangeCoord) <= largestRangeCoord.Range)
{
count++;
}
}
Console.WriteLine(count);
var naiive = (coords.Select(c => c.X).Average(), coords.Select(c => c.Y).Average(), coords.Select(c => c.Z).Average());
Coordinate winner = new Coordinate {
X = (long)Math.Round(naiive.Item1), Y = (long)Math.Round(naiive.Item2), Z = (long)Math.Round(naiive.Item3)
};
var coordsCount = coords.Count(c => ManhattanDistance(c, winner) <= c.Range);
// sieve by powers of 10
for (int t = 0; t < 7; t++)
{
Coordinate tempWinner = winner;
int pow = (int)Math.Pow(10, t);
int start = -50000000 / pow;
int end = 50000000 / pow;
int step = Math.Max(2000000 / pow, 1);
for (int i = start; i < end; i += step)
{
for (int j = start; j < end; j += step)
{
for (int k = start; k < end; k += step)
{
var naiiveC = new Coordinate
{
X = tempWinner.X + i,
Y = tempWinner.Y + j,
Z = tempWinner.Z + k
};
var abc = coords.Count(c => ManhattanDistance(c, naiiveC) <= c.Range);
tempWinner = coordsCount >= abc ? tempWinner : naiiveC;
coordsCount = coordsCount >= abc ? coordsCount : abc;
}
}
}
bool winnerWillChange = coords.Count(c => ManhattanDistance(c, tempWinner) <= c.Range) >
coords.Count(c => ManhattanDistance(c, winner) <= c.Range);
winner = winnerWillChange
? tempWinner
: winner;
Console.WriteLine($"t = {t}, coordCount = {coordsCount}, coord: X = {winner.X}, Y = {winner.Y}, Z = {winner.Z}");
if (winnerWillChange)
{
t = -1;
}
}
// Now for completeness check again with a sieve decreasing in size by a half each time (slightly finer than above)
// TODO Methodise this for sieve size t
for (int t = 0; t < 26; t++)
{
Coordinate tempWinner = winner;
int pow = (int)Math.Pow(2, t);
int start = -50000000 / pow;
int end = 50000000 / pow;
int step = Math.Max(2000000 / pow, 1);
for (int i = start; i < end; i += step)
{
for (int j = start; j < end; j += step)
{
for (int k = start; k < end; k += step)
{
var naiiveC = new Coordinate
{
X = tempWinner.X + i,
Y = tempWinner.Y + j,
Z = tempWinner.Z + k
};
var abc = coords.Count(c => ManhattanDistance(c, naiiveC) <= c.Range);
tempWinner = coordsCount >= abc ? tempWinner : naiiveC;
coordsCount = coordsCount >= abc ? coordsCount : abc;
}
}
}
bool winnerWillChange = coords.Count(c => ManhattanDistance(c, tempWinner) <= c.Range) >
coords.Count(c => ManhattanDistance(c, winner) <= c.Range);
winner = winnerWillChange
? tempWinner
: winner;
Console.WriteLine($"t = {t}, coordCount = {coordsCount}, coord: X = {winner.X}, Y = {winner.Y}, Z = {winner.Z}");
if (winnerWillChange)
{
t = -1;
}
}
Console.ReadLine();
}
