using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

namespace 避免回溯方法
{
  class Program
  {
    static void Main(string[] args)
    {
      string path = AppDomain.CurrentDomain.BaseDirectory;

      List<string> fileList1 = new List<string>();
      FunctionHuishuo(path, ref fileList1);

      List<string> fileList2 = new List<string>();
      FunctionQueue(path, ref fileList2);

      List<string> fileList3 = new List<string>();
      FunctionStack(path, ref fileList3);
    }

    /// <summary>
    /// 回溯法
    /// </summary>
    /// <param name="path"></param>
    /// <param name="fileList"></param>
    private static void FunctionHuishuo(string path, ref List<string> fileList)
    {
      if (true)
      {
        string[] files = null;
        try
        {
          files = Directory.GetFiles(path);
        }
        catch { }

        if (files != null && files.Length > 0)
        {
          fileList.AddRange(files);
        }
      }

      if (true)
      {
        string[] folders = null;
        try
        {
          folders = Directory.GetDirectories(path);
        }
        catch { }

        if (folders != null && folders.Length > 0)
        {
          foreach (string folder in folders)
          {
            FunctionHuishuo(folder, ref fileList);
          }
        }
      }
    }

    /// <summary>
    /// 堆栈法
    /// </summary>
    /// <param name="path"></param>
    private static void FunctionStack(string path, ref List<string> fileList)
    {
      Stack<string> stack = new Stack<string>();
      stack.Push(path);

      while (stack.Count > 0)
      {
        string dir = stack.Pop();

        string[] files = null;
        try
        {
          files = Directory.GetFiles(dir);
        }
        catch { }

        if (files != null && files.Length > 0)
        {
          fileList.AddRange(files);
        }

        string[] folders = null;
        try
        {
          folders = Directory.GetDirectories(dir);
        }
        catch { }

        if (folders != null && folders.Length > 0)
        {
          foreach (string folder in folders)
          {
            stack.Push(folder);
          }
        }
      }
    }

    /// <summary>
    /// 队列法
    /// </summary>
    /// <param name="path"></param>
    private static void FunctionQueue(string path, ref List<string> fileList)
    {
      Queue<string> queue = new Queue<string>();

      queue.Enqueue(path);

      while (queue.Count > 0)
      {
        string dir = queue.Dequeue();

        string[] files = null;
        try
        {
          files = Directory.GetFiles(dir);
        }
        catch { }

        if (files != null && files.Length > 0)
        {
          fileList.AddRange(files);
        }

        string[] folders = null;
        try
        {
          folders = Directory.GetDirectories(dir);
        }
        catch { }

        if (folders != null && folders.Length > 0)
        {
          foreach (string folder in folders)
          {
            queue.Enqueue(folder);
          }
        }
      }
    }
  }
}