using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        var walls = new List<int> { 10, 11, 12, 13, 14, 15 };

        var indexStart = 3;

        var indexDoor = 1;

        var indexDiff = indexDoor - indexStart;

        var wallCountPathA = 1 + Math.Abs(indexDiff);

        var wallCountPathB = 2 + walls.Count - wallCountPathA;

        // Indices

        var wallIndicesPathA = new List<int>(wallCountPathA);

        var wallIndicesPathB = new List<int>(wallCountPathB);

        // Walls

        var wallsPathA = new List<int>(wallCountPathA);

        var wallsPathB = new List<int>(wallCountPathB);

        var directionA = Math.Sign(indexDiff);

        for (var i = 0; i < Math.Max(wallCountPathA, wallCountPathB); i++)

        {

            if (i < wallCountPathA)

            {

                var indexA = indexStart + (directionA * i);

                wallIndicesPathA.Add(indexA);  // Indices

                wallsPathA.Add(walls[indexA]); // Walls

            }

            if (i < wallCountPathB)

            {

                var indexB = (walls.Count + indexStart - (directionA * i)) % walls.Count;

                wallIndicesPathB.Add(indexB);  // Indices

                wallsPathB.Add(walls[indexB]); // Walls

            }

        }

        Console.WriteLine("Wall indices in path A: [ " + string.Join(", ", wallIndicesPathA) + " ]");

        Console.WriteLine("Wall indices in path B: [ " + string.Join(", ", wallIndicesPathB) + " ]");

        Console.WriteLine();

        Console.WriteLine("Walls in path A: [ " + string.Join(", ", wallsPathA) + " ]");

        Console.WriteLine("Walls in path B: [ " + string.Join(", ", wallsPathB) + " ]");

    }

}