public class SnailSolution
{
    public static int[] Snail(int[][] array)
    {
        int left = 0;
        int top = 0;
        int right = array[0].Length;
        int bottom = array.Length;
        int row = 0;
        int col = 0;
        var list = new System.Collections.Generic.List<int>();

        int size = bottom * right;
        if (size == 0)
            return System.Array.Empty<int>();

        while (list.Count < size - 1)
        {

            // go right
            while (col < right - 1)
            {
                list.Add(array[row][col++]);
            }

            ++top;

            // go down
            while (row < bottom - 1)
            {
                list.Add(array[row++][col]);
            }

            --right;

            // go left
            while (col > left)
            {
                list.Add(array[row][col--]);
            }

            --bottom;

            // go up
            while (row > top)
            {
                list.Add(array[row--][col]);
            }

            ++left;
        }

        list.Add(array[row][col]);

        return list.ToArray();
    }
}