private BFSInfo CalculateBFSInfo(int x, int y, int[][] grid)
{
BFSInfo result = new BFSInfo();
bool[,] selected = new bool[grid.Length, grid[0].Length];
LinkedList <int[]> queue = new LinkedList <int[]>();
queue.AddLast(new int[] { x, y, 0 });
while (queue.Count != 0)
{
var value = queue.First.Value;
queue.RemoveFirst();
if (value[0] == grid.Length - 1 && value[1] == grid[0].Length - 1)
{
result.Result = value[2];
var lessValue = value[2] - 1;
while (result.Obstacles.Count != 0)
{
if (result.Obstacles.Last.Value[2] >= lessValue)
{
result.Obstacles.RemoveLast();
}
else
{
break;
}
}
break;
}
IEnumerable <int[]> nextPositions = GetNextPositions(value, grid);
var nextValue = value[2] + 1;
foreach (var item in nextPositions.Where(e => !selected[e[0], e[1]]))
{
if (grid[item[0]][item[1]] == 1)
{
result.Obstacles.AddLast(new int[] { item[0], item[1], nextValue });
}
else
{
queue.AddLast(new int[] { item[0], item[1], nextValue });
}
selected[item[0], item[1]] = true;
}
}
return(result);
}
public int ShortestPath(int[][] grid, int k)
{
if (k >= grid.Length + grid[0].Length - 3)
{
return(grid.Length + grid[0].Length - 2);
}
BFSInfo[,] infos = new BFSInfo[grid.Length, grid[0].Length];
int?[,,] solutions = new int?[grid.Length, grid[0].Length, k + 1];
for (int i = 0; i <= k; i++)
{
solutions[grid.Length - 1, grid[0].Length - 1, i] = 0;
}
return(ShortestPath(0, 0, k, grid, infos, solutions));
}