dorin

ublic static int numPaths (int[][] mat,
             int x1, int y1, int x2, int y2)
    {
        return counterTracks(mat,x1,y1,x2,y2) ;

    }

    private static int counterTracks (int[][] mat,
             int x1, int y1, int x2, int y2)
    {
            if((x1<0 )||( y1<0 ) )
            {
                return 0;
            }

            if((x1 == mat.length )|| (y1 == mat.length))
            {
                return 0;
            }
            if((x1==x2) || (y1==y2))
            {
                return 1;
            }
             if(x1>y1)
             {
                 return 0;
             }

             if(mat[x1][y1] == -1)
             {
                 return 0;
             }

             int counter = mat[x1][y1];
            mat[x1][y1]=-1;

            int sum= counterTracks(mat,x1-1,y1,x2,y2) + counterTracks(mat,x1,y1-1,x2,y2)
            +counterTracks(mat,x1+1,y1,x2,y2) + counterTracks(mat,x1,y1+1,x2,y2);

            mat[x1][y1]= counter;
            return sum;
    }