设计模式——迭代器模式

最新推荐文章于 2025-04-07 18:11:12 发布

原创最新推荐文章于 2025-04-07 18:11:12 发布 · 628 阅读

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本文介绍了一种基于C#实现的树形数据结构及其遍历方法，并通过具体实例展示了如何利用前序遍历和Lambda表达式进行节点的筛选。

/// <summary>
        /// 测试枚举器
        /// </summary>
        private static void TestItemerator()
        {
            var family = new Tree<Person>(new Node<Person>(new Person { Name = "Mr.Zhao", Birthday = "1983-01-13" },
                new Node<Person>(new Person { Name = "Mr.Zhao's Son1", Birthday = "2012-01-12" },
                    new Node<Person>(new Person { Name = "Son1's Son11", Birthday = "2025-01-11" }, null, null),
                    new Node<Person>(new Person { Name = "Son1's Son12", Birthday = "2025-01-11" }, null, null)),
                new Node<Person>(new Person { Name = "Mr.Zhao's Son2", Birthday = "2012-01-12" },
                    new Node<Person>(new Person { Name = "Son2's Son21", Birthday = "2025-01-11" }, null, null),
                    new Node<Person>(new Person { Name = "Son2's Son22", Birthday = "2025-01-11" }, null, null))));
            foreach (var p in family.Preorder)
                Console.WriteLine("{0}=>{1}", p.Name, p.Birthday);
            family.Where(p => string.Compare(p.Birthday, "2014-01-13") > 0).ToList().ForEach(p =>
            {
                Console.WriteLine("家族成员【{0}=>{1}】在2014-01-13之后出生", p.Name, p.Birthday);
            });
        }

1、树节点定义：

/// <summary>
    /// 泛型树节点
    /// </summary>
    /// <typeparam name="T"></typeparam>
    public class Node<T>
    {
        public Node() { }
        public Node<T> Left { get; set; }
        public Node<T> Right { get; set; }
        public T Data { get; set; }

        public Node(T d, Node<T> left, Node<T> right)
        {
            Data = d;
            Left = left;
            Right = right;
        }
    }

2、树定义：

/// <summary>
    /// 树：根节点、构造函数
    /// </summary>
    /// <typeparam name="T"></typeparam>
    public class Tree<T>
    {
        Node<T> root;
        public Tree() { }
        public Tree(Node<T> head)
        {
            this.root = head;
        }

        public IEnumerable<T> Preorder
        {
            get { return ScanPreorder(root); }
        }

        /// <summary>
        /// 带委托的过滤器
        /// </summary>
        /// <param name="filter">带条件的委托方法，返回真假</param>
        /// <returns></returns>
        public IEnumerable<T> Where(Func<T,bool> filter)
        { 
            foreach(var p in ScanPreorder(root))
            {
                if (filter(p))
                    yield return p;
            }
        }


        /// <summary>
        /// 遍历树节点
        /// （前序遍历：根=>左节点=>右节点）
        /// </summary>
        /// <param name="root"></param>
        /// <returns></returns>
        private IEnumerable<T> ScanPreorder(Node<T> root)
        {
            yield return root.Data;
            if (root.Left != null)
            {
                foreach (var p in ScanPreorder(root.Left)) //所有左子树
                {
                    yield return p;
                }
            }

            if (root.Right != null)
            {
                foreach (var r in ScanPreorder(root.Right))//所有右子树
                {
                    yield return r;
                }
            }
        }

    }