private static int GetBfsEscapeLength(char[, ,] labyrinth, Position startPosition)
{
int levelsCount = labyrinth.GetLength(0),
rowsCount = labyrinth.GetLength(1),
colsCount = labyrinth.GetLength(2);
Position[, ,] predecessors = new Position[levelsCount, rowsCount, colsCount];
Queue<Position> toVisit = new Queue<Position>();
toVisit.Enqueue(startPosition);
Position currentPosition;
bool exitFound = false;
do
{
currentPosition = toVisit.Dequeue();
//visited[currentPosition.Level, currentPosition.Row, currentPosition.Col] = true;
List<Position> neighborPositions = GetNeighborPositions(currentPosition, labyrinth);
labyrinth[currentPosition.Level, currentPosition.Row, currentPosition.Col] = Impassable;
foreach (var position in neighborPositions)
{
if (!IsEscapePosition(position, levelsCount, rowsCount, colsCount))
{
toVisit.Enqueue(position);
predecessors[position.Level, position.Row, position.Col] = currentPosition;
}
else
{
exitFound = true;
}
}
}
while (!exitFound && toVisit.Count > 0);
int escapeLength = 1;
Position backTrackPosition = currentPosition;
while (!backTrackPosition.Equals(startPosition))
{
backTrackPosition = predecessors[backTrackPosition.Level, backTrackPosition.Row, backTrackPosition.Col];
escapeLength++;
}
return escapeLength;
}
private static bool IsInLabyrinth(Position currentPosition, int levelsCount, int rowsCount, int colsCount)
{
if (currentPosition.Level >= 0 && currentPosition.Level < levelsCount &&
currentPosition.Row >= 0 && currentPosition.Row < rowsCount &&
currentPosition.Col >= 0 && currentPosition.Col < colsCount)
{
return true;
}
return false;
}
private static List<Position> GetNeighborPositions(Position currentPosition, char[, ,] labyrinth)
{
int levelsCount = labyrinth.GetLength(0),
rowsCount = labyrinth.GetLength(1),
colsCount = labyrinth.GetLength(2);
List<Position> neighborPositions = new List<Position>();
if (IsInLabyrinth(currentPosition, levelsCount, rowsCount, colsCount))
{
neighborPositions.Add(new Position(currentPosition.Level, currentPosition.Row + 1, currentPosition.Col));
neighborPositions.Add(new Position(currentPosition.Level, currentPosition.Row, currentPosition.Col + 1));
neighborPositions.Add(new Position(currentPosition.Level, currentPosition.Row - 1, currentPosition.Col));
neighborPositions.Add(new Position(currentPosition.Level, currentPosition.Row, currentPosition.Col - 1));
if (labyrinth[currentPosition.Level, currentPosition.Row, currentPosition.Col] == LadderUp)
{
neighborPositions.Add(new Position(currentPosition.Level + 1, currentPosition.Row, currentPosition.Col));
}
if (labyrinth[currentPosition.Level, currentPosition.Row, currentPosition.Col] == LadderDown)
{
neighborPositions.Add(new Position(currentPosition.Level - 1, currentPosition.Row, currentPosition.Col));
}
neighborPositions.RemoveAll(pos => !IsValidPosition(pos, labyrinth));
}
return neighborPositions;
}
private static bool IsValidPosition(Position pos, char[, ,] labyrinth)
{
int levelsCount = labyrinth.GetLength(0),
rowsCount = labyrinth.GetLength(1),
colsCount = labyrinth.GetLength(2);
if (IsInLabyrinth(pos, levelsCount, rowsCount, colsCount))
{
if (labyrinth[pos.Level, pos.Row, pos.Col] != Impassable)
{
return true;
}
}
else if (IsEscapePosition(pos, levelsCount, rowsCount, colsCount))
{
return true;
}
return false;
}
private static bool IsEscapePosition(Position currentPosition, int levelsCount, int rowsCount, int colsCount)
{
if (currentPosition.Level < 0 || currentPosition.Level >= levelsCount)
{
if (currentPosition.Row >= 0 && currentPosition.Row < rowsCount &&
currentPosition.Col >= 0 && currentPosition.Col < colsCount)
{
return true;
}
}
return false;
}
