994. Rotting Oranges

public class Solution {
    public int OrangesRotting(int[][] grid) {
        int minutes=0;
        int fresh=0;
        var q = new Queue<(int,int)>();
        for(int i =0; i< grid.Length; i++)
        {
            for(int j =0; j< grid[0].Length; j++)
            {
                if(grid[i][j] ==2)
                   q.Enqueue((i,j));
                else if(grid[i][j] ==1)
                    fresh++;
            }
         }
         int[][] directions = new int[][]{
            new int[] {1,0},
            new int[] {-1,0},
            new int[] {0,1},
            new int[] {0,-1}
         };
        while (q.Count  > 0 && fresh >0)
        {
            int len = q.Count;
            // I only loop one stop from each of initial source nodes
            // propagate or calulate the effect that I need 
            // and then loop again on the second layer I added and so on.
            // So It's multi source BFS in the sense that I do it concurrently 
            //and terminate and concurrently and terminate
            // until all is visited or effect is propagated
            for(int i =0; i< len; i++) 
            {     
                var cell = q.Dequeue();
                foreach(var dir in directions)
                {
                    var x = cell.Item1+  dir[0];
                    var y = cell.Item2 + dir[1];
                    if(x >= 0 && x < grid.Length && y >= 0 && y < grid[0].Length 
                      && grid[x][y] ==1 )
                    {
                        grid[x][y] = 2;
                        q.Enqueue((x,y));
                        fresh--;
                    }
                }
            }
             minutes++;
        }


         return fresh ==0 ? minutes : -1;    
    }

}