static int[,] TypeC(int r, int c)
    {
        int[,] m = new int[r, c];
        int number = 1;

        for (int i = r-1; i >= 0; i--)
        {
            int startR = i;
            for (int j = 0; j < r-startR; j++)
            {
                if (j>c-1) { break; }
                m[startR + j, j] = number; number++;
            }
        }

        for (int i = 1; i < c; i++)
        {
            int startC = i;
            for (int j = 0; j < c - startC; j++)
            {
                if (j > r - 1) { break; }
                m[j, startC + j] = number; number++;
            }
        }

        return m;
    }

    static int[,] TypeD(int r, int c)
    {
        int[,] m = new int[r, c];
        int number = 1;
        int indexR = 0;
        int indexC = 0;

        while (number<=r*c)
        {
            m[indexR, indexC] = number;
            number++;;

            bool canGoDown = (indexR + 1) < r && m[indexR + 1, indexC] == 0 && !((indexC - 1) >= 0 && m[indexR, indexC - 1] == 0);
            if (canGoDown) { indexR++; continue; }
            bool canGoRight = (indexC + 1) < c && m[indexR, indexC + 1] == 0;
            if (canGoRight) { indexC++; continue; }
            bool canGoUp = (indexR - 1) >= 0 && m[indexR - 1, indexC] == 0;
            if (canGoUp) { indexR--; continue; }
            bool canGoLeft = (indexC - 1) >= 0 && m[indexR, indexC - 1] == 0;
            if (canGoLeft) { indexC--; continue; }
        }

        return m;
    }