/// <summary>
/// Returns all available coordinates in the map for the given board square
/// </summary>
private List <BoardSquare> GetAllAvailableNeighbours(BoardSquare center)
{
List <BoardSquare> result = new List <BoardSquare>();
if ((center.X < m_Map.Size && center.X >= 0) &&
(center.Y < m_Map.Size && center.Y >= 0))
{
if (center.X - 1 >= 0 && m_Map.GetContent(center.X - 1, center.Y) == "_")
{
result.Add(new BoardSquare(center.X - 1, center.Y));
}
if (center.X + 1 < m_Map.Size && m_Map.GetContent(center.X + 1, center.Y) == "_")
{
result.Add(new BoardSquare(center.X + 1, center.Y));
}
if (center.Y - 1 >= 0 && m_Map.GetContent(center.X, center.Y - 1) == "_")
{
result.Add(new BoardSquare(center.X, center.Y - 1));
}
if (center.Y + 1 < m_Map.Size && m_Map.GetContent(center.X, center.Y + 1) == "_")
{
result.Add(new BoardSquare(center.X, center.Y + 1));
}
}
if (result.Count > 4)
{
throw new InvalidOperationException("A point in the map has 4 neighbours at most");
}
return(result);
}
/// <summary>
/// Gets all neighbours which has a numeric value.
/// </summary>
/// <param name="center"></param>
/// <returns>All neighbours for the given square which has a numeric value</returns>
private List <BoardSquare> GetAllNeighboursWhichisPartOfSolution(BoardSquare center)
{
List <BoardSquare> result = new List <BoardSquare>();
if ((center.X < m_Map.Size && center.X >= 0) &&
(center.Y < m_Map.Size && center.Y >= 0))
{
int numeric;
if (center.X - 1 >= 0 && int.TryParse(m_Map.GetContent(center.X - 1, center.Y), out numeric))
{
result.Add(new BoardSquare(center.X - 1, center.Y));
}
if (center.X + 1 < m_Map.Size && int.TryParse(m_Map.GetContent(center.X + 1, center.Y), out numeric))
{
result.Add(new BoardSquare(center.X + 1, center.Y));
}
if (center.Y - 1 >= 0 && int.TryParse(m_Map.GetContent(center.X, center.Y - 1), out numeric))
{
result.Add(new BoardSquare(center.X, center.Y - 1));
}
if (center.Y + 1 < m_Map.Size && int.TryParse(m_Map.GetContent(center.X, center.Y + 1), out numeric))
{
result.Add(new BoardSquare(center.X, center.Y + 1));
}
}
if (result.Count > 4)
{
throw new InvalidOperationException("A point in the map has 4 neighbours at most");
}
return(result);
}
private List <BoardSquare> PrepareSolutionPath(BoardSquare start, BoardSquare finish)
{
List <BoardSquare> result = new List <BoardSquare>();
BoardSquare temp = GetSmallestValueNeighbour(finish);
result.Add(temp);
while (!temp.Equals(start))
{
temp = GetSmallestValueNeighbour(temp);
result.Add(temp);
}
result.Reverse();
return(result);
}
/// <summary>
/// Picks the square whose numeric value is smallest
/// </summary>
private BoardSquare GetSmallestValueNeighbour(BoardSquare square)
{
List <BoardSquare> list = GetAllNeighboursWhichisPartOfSolution(square);
BoardSquare smallest = list[0];
for (int i = 1; i < list.Count; i++)
{
if (m_Visited[list[i]] < m_Visited[smallest])
{
smallest = list[i];
}
else if (m_Visited[list[i]] == m_Visited[m_Map.GetSpecificSquare("0")])
{
smallest = list[i];
}
}
return(smallest);
}
/// <summary>
/// Finds the path between start and finish using Breadth First Search
/// </summary>
public List <BoardSquare> Find()
{
BoardSquare start = m_Map.GetSpecificSquare("0");
BoardSquare finish = m_Map.GetSpecificSquare("F");
Queue <BoardSquare> toBeProcessed = new Queue <BoardSquare>();
toBeProcessed.Enqueue(start);
int order = 0;
m_VisitInfo[start] = true;
var current = start;
m_Visited[current] = order;
while (toBeProcessed.Count > 0)
{
var point = toBeProcessed.Dequeue();
var neighbours = GetAllAvailableNeighbours(point);
foreach (var item in neighbours)
{
if (m_VisitInfo[item] == false)
{
toBeProcessed.Enqueue(item);
m_VisitInfo[point] = true;
m_Visited[item] = order;
m_Map.Update(item.X, item.Y, order.ToString());
}
}
order += 1;
}
List <BoardSquare> result = PrepareSolutionPath(start, finish);
return(result);
}
