public void Part2()
{
char[,] masterGrid = new char[SideLength * 8, SideLength * 8];
// make a copy of the arranged tiles with the edges removed
int xOffset = 0;
int yOffset = 0;
for (int i = 0; i < SideLength; i++)
{
for (int j = 0; j < SideLength; j++)
{
IdView idView = Part1IdViews[i, j];
Tile tile = Tiles.FirstOrDefault(t => t.Id == idView.Id);
char[,] grid = tile.Transform(idView.ViewNum);
for (int x = 0; x < 8; x++)
{
for (int y = 0; y < 8; y++)
{
masterGrid[x + xOffset, y + yOffset] = grid[x, y];
}
}
yOffset += 8;
}
xOffset += 8;
yOffset = 0;
}
int rotations = 0;
int nSerpents;
// locate the view that has serpents by rotating or flipping the grid, then searching
while ((nSerpents = FindSerpents(masterGrid)) == 0 && rotations < 8)
{
if (rotations == 4)
{
// we've gone all the way around. Flip it & search the flipped rotations
masterGrid = Tile.Flip(masterGrid);
}
else
{
masterGrid = Tile.Rotate(masterGrid);
}
rotations++;
}
// Finally! count the non-serpent marks
int nonMonster = 0;
for (int y = 0; y < masterGrid.GetLength(0); y++)
{
for (int x = 0; x < masterGrid.GetLength(0); x++)
{
nonMonster += masterGrid[x, y] == '#' ? 1 : 0;
}
}
Console.WriteLine("Part2: {0}", nonMonster);
}
public void FindPairings(List <Tuple <IdView, IdView> > horizCandidates, List <Tuple <IdView, IdView> > vertCandidates)
{
foreach (Tile tile1 in Tiles)
{
foreach (Tile tile2 in Tiles)
{
if (tile1.Id != tile2.Id)
{
for (int i = 0; i < 8; i++)
{
for (int j = 0; j < 8; j++)
{
if (tile1.Views[i].IsHorizontalMatch(tile2.Views[j]))
{
IdView one = new IdView(tile1.Id, i);
IdView two = new IdView(tile2.Id, j);
Tuple <IdView, IdView> pair = new Tuple <IdView, IdView>(one, two);
horizCandidates.Add(pair);
}
if (tile1.Views[i].IsVerticalMatch(tile2.Views[j]))
{
IdView one = new IdView(tile1.Id, i);
IdView two = new IdView(tile2.Id, j);
Tuple <IdView, IdView> pair = new Tuple <IdView, IdView>(one, two);
vertCandidates.Add(pair);
}
}
}
}
}
}
}
public void Part1()
{
List <Tile> candidates = new List <Tile>(Tiles);
IdView[,] idViews = new IdView[SideLength, SideLength];
FindPairings(HorizontalCandidates, VerticalCandidates);
List <long> usedTiles = new List <long>();
foreach (Tuple <IdView, IdView> pair in HorizontalCandidates)
{
usedTiles.Clear();
usedTiles.Add(pair.Item1.Id);
idViews[0, 0] = pair.Item1;
if (RecursiveMatch(usedTiles, idViews, 0, 0))
{
break;
}
}
Console.WriteLine("Part1: {0}", Result);
}
private bool RecursiveMatch(List <long> usedTiles, IdView[,] idViews, int x, int y)
{
// always match sideways until end of row (x), then start at next column (y)
if (usedTiles.Count == Tiles.Count)
{
// result is in the 4 corners of idViews
Result = idViews[0, 0].Id * idViews[SideLength - 1, 0].Id * idViews[0, SideLength - 1].Id * idViews[SideLength - 1, SideLength - 1].Id;
// save idViews for part 2
Part1IdViews = (IdView[, ])idViews.Clone();
return(true); // all tiles arranged!
}
else if (x < SideLength - 1)
{
IdView idView = idViews[x, y];
var horizontals = HorizontalCandidates.Where(p => idView.Id == p.Item1.Id &&
idView.ViewNum == p.Item1.ViewNum &&
usedTiles.Contains(p.Item2.Id) == false);
foreach (Tuple <IdView, IdView> pair in horizontals)
{
IdView[,] partialViews = (IdView[, ])idViews.Clone();
List <long> tmpUsedTiles = new List <long>(usedTiles);
tmpUsedTiles.Add(pair.Item2.Id);
partialViews[x + 1, y] = pair.Item2;
if (RecursiveMatch(tmpUsedTiles, partialViews, x + 1, y))
{
return(true);
}
}
return(false);
}
else
{
x = 0;
IdView idView = idViews[x, y];
var verticals = VerticalCandidates.Where(p => idView.Id == p.Item1.Id &&
idView.ViewNum == p.Item1.ViewNum &&
usedTiles.Contains(p.Item2.Id) == false);
foreach (Tuple <IdView, IdView> pair in verticals)
{
IdView[,] partialViews = (IdView[, ])idViews.Clone();
List <long> tmpUsedTiles = new List <long>(usedTiles);
tmpUsedTiles.Add(pair.Item2.Id);
partialViews[x, y + 1] = pair.Item2;
if (RecursiveMatch(tmpUsedTiles, partialViews, x, y + 1))
{
return(true);
}
}
return(false); // temp
}
}