CodeWars/4kyu/snail/solution.cs

using System;

public class SnailSolution {
  private static void Update(ref int dx, ref int dy) {
    int newDx = -dy, newDy = dx;
    dy = newDy;
    dx = newDx;
  }

  public static int[] Snail(int[][] array) {
    if (array.Length == 1 && array[0].Length == 0) {
      return new int[] {};
    }

    int[] result = new int[array.Length * array.Length];

    int y = 0, x = 0;
    int dy = 0, dx = 1;

    int left = -1, right = array.Length;
    int top = 0, bottom = array.Length;

    for (var i = 0; i < result.Length; i++) {
      result[i] = array[y][x];

      if (dx != 0 && x + dx <= left) {
        left++;
        Update(ref dx, ref dy);
      } else if (dx != 0 && x + dx >= right) {
        right--;
        Update(ref dx, ref dy);
      } else if (dy != 0 && y + dy <= top) {
        top++;
        Update(ref dx, ref dy);
      } else if (dy != 0 && y + dy >= bottom) {
        bottom--;
        Update(ref dx, ref dy);
      }

      x += dx;
      y += dy;
    }

    return result;
  }
}