哈夫曼樹

using System;
using System.Collections.Generic;
using System.Linq;

namespace 哈夫曼樹
{
    class Program
    {
        public static List<HuffmanNode> huffmanNodes= new List<HuffmanNode>();//哈夫曼樹節點集合
        public static List<Node> nodes = new List<Node>();//基本節點集合 只有數值和權重
        static void Main(string[] args)
        {
            //新增節點（權重，字元）
            nodes.Add(new Node(5, "a"));
            nodes.Add(new Node(32, "b"));
            nodes.Add(new Node(18, "c"));
            nodes.Add(new Node(7, "d"));
            nodes.Add(new Node(25, "e"));

            //將每個節點轉換成哈夫曼樹的節點
            foreach (var node in nodes)
            {
                HuffmanNode huffman = new HuffmanNode();
                huffman.value = node.Value;
                huffman.weight = node.Weight;
                huffmanNodes.Add(huffman);
            }

            //生成哈夫曼樹
            while (huffmanNodes.Count > 1)
            {
                //將所有節點按權重升序排序
                var sort =
                    from node in huffmanNodes
                    orderby node.weight
                    select node;
                //選出權重最小的兩個節點
                var min = sort.Take(2).ToArray();
                //生成一個父節點 權重為兩個權重最小節點的權重和
                HuffmanNode huffman = new HuffmanNode();
                huffman.weight = min[0].weight + min[1].weight;
                huffman.left = min[0];
                huffman.right = min[1];
                //為兩個權重最小節點新增父節點
                min[0].parent = huffman;
                min[1].parent = huffman;
                //在集合中移除兩個最小節點
                huffmanNodes.Remove(min[0]);
                huffmanNodes.Remove(min[1]);
                //將父節點新增進集合中
                huffmanNodes.Add(huffman);
            }

            visitTree(huffmanNodes[0], " "," " );

            Console.ReadKey();
        }

        //哈夫曼編碼輸出 左子樹為0 右子樹為1
        public  static void visitTree(HuffmanNode node, String prefixStr, String addStr)
        {
            if (node != null)
            {
                if (!string .IsNullOrEmpty(node.value))
                    Console.WriteLine(node.value.ToString() + ":" + prefixStr + addStr);
                visitTree(node.left, prefixStr + addStr, "0");
                visitTree(node.right, prefixStr + addStr, "1");
            }
        }
    }

    /// <summary>
    /// 定義個Node節點類 用於新增操作
    /// </summary>
    public class Node
    {
        public int Weight { get; set; }//權重
        public String Value { get; set; }//值
        public Node(int weight, string value)
        {
            Weight = weight;
            Value = value;
        }
    }

    /// <summary>
    /// 哈夫曼樹節點類
    /// </summary>
    public class HuffmanNode
    {
        public int weight;//權重
        public String value = "";//值
        public HuffmanNode parent;//父節點
        public HuffmanNode left;//左孩子
        public HuffmanNode right;//右孩子

    }
}