public static void Day13()
{
//int favoriteNum = 10;
//var destination = new Day13Location() {location = new Tuple<int, int>(7, 4)};
int favoriteNum = 1358;
var destination = new Day13Location()
{
location = new Tuple <int, int>(31, 39)
};
Func <Day13Location, Day13Location, double> distanceFunc = (Day13Location l1, Day13Location l2) => Math.Sqrt((l2.x - l1.x) * (l2.x - l1.x) + (l2.y - l1.y) * (l2.y - l1.y));
int [,] officeSpace = new int[255, 255];
var cameFrom = new Dictionary <Day13Location, Day13Location>();
var currentLocation = new Day13Location()
{
location = new Tuple <int, int>(1, 1), gScore = 0
};
currentLocation.fScore = distanceFunc(currentLocation, destination);
Func <int, int, bool> IsSpace = (x, y) =>
{
int z = (x * x + 3 * x + 2 * x * y + y + y * y) + favoriteNum;
int onBits = 0;
for (int i = 0; i < 15; i++)
{
if ((z & (int)Math.Pow(2, i)) > 0)
{
onBits++;
}
}
return(onBits % 2 == 0);
};
var openSet = new List <Day13Location>();
openSet.Add(currentLocation);
var closedSet = new List <Day13Location>();
bool success = false;
while (openSet.Count > 0)
{
openSet.Sort();
currentLocation = openSet.First();
if (currentLocation.Equals(destination))
{
Console.WriteLine("Success!");
success = true;
break;
}
openSet.Remove(currentLocation);
closedSet.Add(currentLocation);
double nextGScore = currentLocation.gScore + 1;
for (int x = -1; x < 2; x++)
{
for (int y = -1; y < 2; y++)
{
if ((x != 0 && y != 0) || x == 0 && y == 0)
{
continue; // cardinal directions only, no diagonal and avoid the current location
}
var neighborTuple = new Tuple <int, int>(currentLocation.x + x, currentLocation.y + y);
if (neighborTuple.Item1 < 0 || neighborTuple.Item2 < 0)
{
continue; // negative values are invalid
}
if (IsSpace(currentLocation.x + x, currentLocation.y + y))
{
double possibleFScore = distanceFunc(currentLocation, destination) + currentLocation.gScore;
var neighbor = openSet.FirstOrDefault(l => l.Equals(new Day13Location()
{
location = neighborTuple
}));
if (neighbor != null && neighbor.gScore > nextGScore)
{
openSet.Remove(neighbor);
}
neighbor = closedSet.FirstOrDefault(l => l.Equals(new Day13Location()
{
location = neighborTuple
}));
if (neighbor != null && neighbor.gScore > nextGScore)
{
closedSet.Remove(neighbor);
}
if (!closedSet.Contains(neighbor) && !openSet.Contains(neighbor))
{
if (null == neighbor)
{
neighbor = new Day13Location()
{
location = neighborTuple
}
}
;
openSet.Add(neighbor);
neighbor.gScore = nextGScore;
neighbor.fScore = nextGScore + possibleFScore;
cameFrom[neighbor] = currentLocation;
}
}
}
}
}
// print out the path
Console.WriteLine(currentLocation);
int steps = 0;
while (cameFrom.TryGetValue(currentLocation, out currentLocation))
{
Console.WriteLine(currentLocation);
steps++;
}
Console.WriteLine($"Took {steps} steps");
}
public static void Day13Part2()
{
int favoriteNum = 1358;
Func <Day13Location, Day13Location, double> distanceFunc = (Day13Location l1, Day13Location l2) => Math.Sqrt((l2.x - l1.x) * (l2.x - l1.x) + (l2.y - l1.y) * (l2.y - l1.y));
var currentLocation = new Day13Location()
{
location = new Tuple <int, int>(1, 1), gScore = 0
};
Func <int, int, bool> IsSpace = (x, y) =>
{
int z = (x * x + 3 * x + 2 * x * y + y + y * y) + favoriteNum;
int onBits = 0;
for (int i = 0; i < 15; i++)
{
if ((z & (int)Math.Pow(2, i)) > 0)
{
onBits++;
}
}
return(onBits % 2 == 0);
};
var openSet = new List <Day13Location>();
openSet.Add(currentLocation);
var closedSet = new List <Day13Location>();
bool success = false;
while (openSet.Count > 0)
{
currentLocation = openSet.First();
openSet.Remove(currentLocation);
closedSet.Add(currentLocation);
double nextGScore = currentLocation.gScore + 1;
if (nextGScore > 50)
{
continue;
}
for (int x = -1; x < 2; x++)
{
for (int y = -1; y < 2; y++)
{
if ((x != 0 && y != 0) || x == 0 && y == 0)
{
continue; // cardinal directions only, no diagonal and avoid the current location
}
var neighborTuple = new Tuple <int, int>(currentLocation.x + x, currentLocation.y + y);
if (neighborTuple.Item1 < 0 || neighborTuple.Item2 < 0)
{
continue; // negative values are invalid
}
if (IsSpace(currentLocation.x + x, currentLocation.y + y))
{
var neighbor = new Day13Location()
{
location = neighborTuple, gScore = nextGScore
};
if (!closedSet.Contains(neighbor) && !openSet.Contains(neighbor))
{
openSet.Add(neighbor);
neighbor.gScore = nextGScore;
}
}
}
}
}
// print out the path
var gScore50Locs = closedSet.Where(l => l.gScore <= 50);
Console.WriteLine($"There are {gScore50Locs.Count()} locations within 50 steps from the start");
}
