具有通用数据的树

using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

public class Tree<T>
{
    public T Data { get; set; }
    public LinkedList<Tree<T>> Children { get; set; } = new LinkedList<Tree<T>>();
    public Task Traverse(Func<T, Task> actionOnNode, int maxDegreeOfParallelism = 1) => Traverse(actionOnNode, new SemaphoreSlim(maxDegreeOfParallelism, maxDegreeOfParallelism));
    private async Task Traverse(Func<T, Task> actionOnNode, SemaphoreSlim semaphore)
    {
        await actionOnNode(Data);
        SafeRelease(semaphore);
        IEnumerable<Task> tasks = Children.Select(async input =>
        {
            await semaphore.WaitAsync().ConfigureAwait(false);
            try
            {
                await input.Traverse(actionOnNode, semaphore).ConfigureAwait(false);
            }
            finally
            {
                SafeRelease(semaphore);
            }
        });
        await Task.WhenAll(tasks);
    }
    private void SafeRelease(SemaphoreSlim semaphore)
    {
        try
        {
            semaphore.Release();
        }
        catch (Exception ex)
        {
            if (ex.Message.ToLower() != "Adding the specified count to the semaphore would cause it to exceed its maximum count.".ToLower())
            {
                throw;
            }
        }
    }

    public async Task<IEnumerable<T>> ToList()
    {
        ConcurrentBag<T> lst = new ConcurrentBag<T>();
        await Traverse(async (data) => lst.Add(data));
        return lst;
    }
    public async Task<int> Count() => (await ToList()).Count();
}

单元测试

using System.Threading.Tasks;
using Xunit;

public class Tree_Tests
{
    [Fact]
    public async Task Tree_ToList_Count()
    {
        Tree<int> head = new Tree<int>();

        Assert.NotEmpty(await head.ToList());
        Assert.True(await head.Count() == 1);

        // child
        var child = new Tree<int>();
        head.Children.AddFirst(child);
        Assert.True(await head.Count() == 2);
        Assert.NotEmpty(await head.ToList());

        // grandson
        child.Children.AddFirst(new Tree<int>());
        child.Children.AddFirst(new Tree<int>());
        Assert.True(await head.Count() == 4);
        Assert.NotEmpty(await head.ToList());
    }

    [Fact]
    public async Task Tree_Traverse()
    {
        Tree<int> head = new Tree<int>() { Data = 1 };

        // child
        var child = new Tree<int>() { Data = 2 };
        head.Children.AddFirst(child);

        // grandson
        child.Children.AddFirst(new Tree<int>() { Data = 3 });
        child.Children.AddLast(new Tree<int>() { Data = 4 });

        int counter = 0;
        await head.Traverse(async (data) => counter += data);
        Assert.True(counter == 10);

        counter = 0;
        await child.Traverse(async (data) => counter += data);
        Assert.True(counter == 9);

        counter = 0;
        await child.Children.First!.Value.Traverse(async (data) => counter += data);
        Assert.True(counter == 3);

        counter = 0;
        await child.Children.Last!.Value.Traverse(async (data) => counter += data);
        Assert.True(counter == 4);
    }
}

这是我的，和艾伦·盖奇的很相似，只是在我看来更传统一点。就我而言，我使用List<T>时没有遇到任何性能问题。如果需要，切换到LinkedList是很容易的。

namespace Overby.Collections
{
    public class TreeNode<T>
    {
        private readonly T _value;
        private readonly List<TreeNode<T>> _children = new List<TreeNode<T>>();

        public TreeNode(T value)
        {
            _value = value;
        }

        public TreeNode<T> this[int i]
        {
            get { return _children[i]; }
        }

        public TreeNode<T> Parent { get; private set; }

        public T Value { get { return _value; } }

        public ReadOnlyCollection<TreeNode<T>> Children
        {
            get { return _children.AsReadOnly(); }
        }

        public TreeNode<T> AddChild(T value)
        {
            var node = new TreeNode<T>(value) {Parent = this};
            _children.Add(node);
            return node;
        }

        public TreeNode<T>[] AddChildren(params T[] values)
        {
            return values.Select(AddChild).ToArray();
        }

        public bool RemoveChild(TreeNode<T> node)
        {
            return _children.Remove(node);
        }

        public void Traverse(Action<T> action)
        {
            action(Value);
            foreach (var child in _children)
                child.Traverse(action);
        }

        public IEnumerable<T> Flatten()
        {
            return new[] {Value}.Concat(_children.SelectMany(x => x.Flatten()));
        }
    }
}

delegate void TreeVisitor<T>(T nodeData);

class NTree<T>
{
    private T data;
    private LinkedList<NTree<T>> children;

    public NTree(T data)
    {
         this.data = data;
        children = new LinkedList<NTree<T>>();
    }

    public void AddChild(T data)
    {
        children.AddFirst(new NTree<T>(data));
    }

    public NTree<T> GetChild(int i)
    {
        foreach (NTree<T> n in children)
            if (--i == 0)
                return n;
        return null;
    }

    public void Traverse(NTree<T> node, TreeVisitor<T> visitor)
    {
        visitor(node.data);
        foreach (NTree<T> kid in node.children)
            Traverse(kid, visitor);
    }
}

简单的递归实现… < 40行代码… 你只需要在类外保留一个对树根的引用， 或者在另一个类中包装它，也许重命名为TreeNode??

下面是我实现的BST:

class BST
{
    public class Node
    {
        public Node Left { get; set; }
        public object Data { get; set; }
        public Node Right { get; set; }

        public Node()
        {
            Data = null;
        }

        public Node(int Data)
        {
            this.Data = (object)Data;
        }

        public void Insert(int Data)
        {
            if (this.Data == null)
            {
                this.Data = (object)Data;
                return;
            }
            if (Data > (int)this.Data)
            {
                if (this.Right == null)
                {
                    this.Right = new Node(Data);
                }
                else
                {
                    this.Right.Insert(Data);
                }
            }
            if (Data <= (int)this.Data)
            {
                if (this.Left == null)
                {
                    this.Left = new Node(Data);
                }
                else
                {
                    this.Left.Insert(Data);
                }
            }
        }

        public void TraverseInOrder()
        {
            if(this.Left != null)
                this.Left.TraverseInOrder();
            Console.Write("{0} ", this.Data);
            if (this.Right != null)
                this.Right.TraverseInOrder();
        }
    }

    public Node Root { get; set; }
    public BST()
    {
        Root = new Node();
    }
}

试试这个简单的例子。

public class TreeNode<TValue>
{
    #region Properties
    public TValue Value { get; set; }
    public List<TreeNode<TValue>> Children { get; private set; }
    public bool HasChild { get { return Children.Any(); } }
    #endregion
    #region Constructor
    public TreeNode()
    {
        this.Children = new List<TreeNode<TValue>>();
    }
    public TreeNode(TValue value)
        : this()
    {
        this.Value = value;
    }
    #endregion
    #region Methods
    public void AddChild(TreeNode<TValue> treeNode)
    {
        Children.Add(treeNode);
    }
    public void AddChild(TValue value)
    {
        var treeNode = new TreeNode<TValue>(value);
        AddChild(treeNode);
    }
    #endregion
}

如果要在GUI上显示这个树，可以使用TreeView和TreeNode。(我认为从技术上讲，你可以创建一个TreeNode而不把它放在GUI上，但它确实比一个简单的自定义TreeNode实现有更多的开销。)