Java實現建立哈夫曼樹__Java

使用Java建立哈夫曼樹代碼如下：

注意事項都在代碼中說了，具體的原理很簡單，我就不多說了：

package data_structure;import java.util.ArrayList;import java.util.Collection;import java.util.Collections;import java.util.LinkedList;import java.util.List;public class HuffmanTree {public static class Node<E>{private E data;private Node lChild;private Node rchild;private float weight;public Node(E data,float weight){this.data=data;this.weight=weight;lChild=null;rchild=null;}public String toString(){String s="[data:"+data.toString()+",weight"+weight+"]";return s; }}@SuppressWarnings({ "rawtypes", "unchecked" })public static <E> Node createTree(List<Node> l){List<Node> list=new ArrayList<>();list.addAll(l);while(list.size()>1){quickSort(list);for(Node node:list)System.out.print(node.data+""+(int)node.weight+" ");System.out.println();Node lChild=list.get(list.size()-1);Node rChild=list.get(list.size()-2);Node parent=new Node("@", lChild.weight+rChild.weight);parent.lChild=lChild;parent.rchild=rChild;list.remove(list.size()-1); //注意這裡都是減去1list.remove(list.size()-1);list.add(parent);}return list.get(0);}/***************快排**************/public static void quickSort(List<Node> list){sort(list,0,list.size()-1);}public static void sort(List<Node> list,int l,int r){if(l<r){int random=(int)(Math.random()*(r-l+1)+l);swap(list, l, random);int i=l,j=r+1;float value=list.get(l).weight;while(true){                 //千萬不能寫成i<j，因為j已經+1了while(i<r&&list.get(++i).weight>value);while(j>l&&list.get(--j).weight<value);if(i>=j)break;swap(list, i, j);}swap(list, l, j);sort(list, l, j-1);sort(list, j+1, r);}}public static void swap(List<Node> list,int l,int r){Node tempNode=list.get(l);list.set(l, list.get(r));list.set(r, tempNode);}    public static void inOrder(Node root){    if(root==null)    return;    inOrder(root.lChild);        System.out.print(root.toString()+"  ");    inOrder(root.rchild);    }        public static void main(String []args){    List<HuffmanTree.Node> list=new LinkedList<>();    list.add(new Node("A", 20));    list.add(new Node("B", 13));    list.add(new Node("C", 5));    list.add(new Node("D", 2));    list.add(new Node("E", 10));    list.add(new Node("F", 7));    list.add(new Node("G", 26));    list.add(new Node("H", 3));    list.add(new Node("I", 2));    /*list.add(new Node("A", 5));    list.add(new Node("B", 15));    list.add(new Node("C", 40));    list.add(new Node("D", 30));    list.add(new Node("E", 10));*/    HuffmanTree.inOrder(HuffmanTree.createTree(list));    }}