// Return the number of moves that were avaiable on this pipe segment.
// If the return value is 1, the move has been made.
private int tryPipe(Pipe p, bool tryHead)
{
if (p.IsConnected)
{
return(0);
}
List <XY> a = p.HeadPath;
List <XY> b = p.TailPath;
XY aPos, bPos;
if (tryHead) // Swap roles of a and b
{
aPos = p.HeadPos;
bPos = p.TailPos;
}
else
{
aPos = p.TailPos;
bPos = p.HeadPos;
}
// See if we can advance deterministically from a, or meet b
List <XY> possibles = findPossibleMoves(aPos, bPos);
if (possibles.Count != 1)
{
return(possibles.Count);
}
// There is one and only one move, so make it *on the current board*
// without cloning a new state.
XY newPos = possibles[0];
if (TheBoard[newPos.Y, newPos.X] == 0)
{
// Propagate this pipe's color into the new position
TheBoard[newPos.Y, newPos.X] = TheBoard[aPos.Y, aPos.X];
// And extend the pipe.
if (tryHead)
{
p.AdvanceHead(newPos);
}
else
{
p.AdvanceTail(newPos);
}
}
else
{
p.IsConnected = true;
}
MovesToGo--;
return(1);
}