public static bool IsIntersection(IContains inter, int move)
{
if (inter.GetSize() <= 2)
{
return(false);
}
int lWidth = inter.GetWidth();
int ActiveMice = 0;
int[] lMousePosition = new int[4];
int[] lMouseDirection = new int[4];
int[] lMouseNextDirection = new int[4];
int[] lMouseByDirection = new int[4];
CoordinateSystem lCoord = CoordinateSystem.GetCoordinateSystem(lWidth);
for (int i = 0; i < 4; i++)
{
int lNeightbor = lCoord.GetNeighbor(move, i);
if (lCoord.OnBoard(lNeightbor) && inter.Contains(lNeightbor))
{
lMousePosition[ActiveMice] = lNeightbor;
lMouseDirection[ActiveMice] = i;
lMouseByDirection[i] = ActiveMice;
if (ActiveMice > 0)
{
lMouseNextDirection[ActiveMice - 1] = i;
}
ActiveMice++;
}
else
{
lMouseByDirection[i] = -1; // no mouse
}
}
if (ActiveMice == 1)
{
return(false);
}
lMouseNextDirection[ActiveMice - 1] = 0; // it's never used!
for (int CurrentMouse = 0; CurrentMouse < ActiveMice - 1; CurrentMouse++)
{
int CurrentMousePosition = lMousePosition[CurrentMouse];
int CurrentMouseDirection = lMouseDirection[CurrentMouse];
int CurrentMouseOriginalDirection = CurrentMouseDirection;
while (CurrentMousePosition != move)
{
int lRightDirection = CoordinateSystem.TurnClockWise(CurrentMouseDirection);
int lRightPosition = lCoord.GetNeighbor(CurrentMousePosition, lRightDirection);
// if (can turn right & move)
if (CoordinateSystem.OnBoard(lRightPosition, lWidth) && inter.Contains(lRightPosition))
{
// yes, turn turn and move
CurrentMousePosition = lRightPosition;
CurrentMouseDirection = lRightDirection;
}
else
{
while (true)
{
int lStraightPosition = lCoord.GetNeighbor(CurrentMousePosition, CurrentMouseDirection);
// if (can go straight) (
if (CoordinateSystem.OnBoard(lStraightPosition, lWidth) && inter.Contains(lStraightPosition))
{
// yes, go straight
CurrentMousePosition = lStraightPosition;
break;
}
else
{
// else, change direction clockwise and try-again (loop)
CurrentMouseDirection = CoordinateSystem.TurnCounterClockWise(CurrentMouseDirection);
}
}
}
}
// right back where we started
int FromDirection = CoordinateSystem.TurnAround(CurrentMouseDirection);
// if mice returned from a direction other than the next direction, then there is a split
if (lMouseNextDirection[CurrentMouse] != FromDirection)
{
return(true);
}
// if mouse came back from original direction then there is a split
if (CurrentMouseOriginalDirection == FromDirection)
{
return(true); // should never reach here
}
// by now we know that the next mouse must merge, so no split
if (CurrentMouse == ActiveMice - 1)
{
return(false);
}
}
return(false);
}