Java实现HuffmanTree

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1.结点类

package edu.tcu.soft.tree;/*结点类*/public class Node{private int weight;// 结点权值private Node parent;// 双亲结点private Node left;// 左孩子结点private Node right;// 右孩子结点public int getWeight() {return weight;}public void setWeight(int weight) {this.weight = weight;}public Node getParent() {return parent;}public void setParent(Node parent) {this.parent = parent;}public Node getLeft() {return left;}public void setLeft(Node left) {this.left = left;}public Node getRight() {return right;}public void setRight(Node right) {this.right = right;}public Node(int weight, Node parent, Node left, Node right) {this.weight = weight;this.parent = parent;this.left = left;this.right = right;}public Node(int weight) {        this.left=null;        this.right=null;        this.parent=null;this.weight = weight;}public Node() {}public int compare(Node o1, Node o2) {return o1.getWeight() - o2.getWeight();}}

2.比较器类

package edu.tcu.soft.tree;import java.util.Comparator;/*权值比较器*/@SuppressWarnings("rawtypes")public class WeightComparator implements Comparator{public int compare(Object o1, Object o2) {        Node node1=(Node)o1;        Node node2=(Node)o2;return node1.getWeight()-node2.getWeight();}}

3.哈夫曼树的实现类

package edu.tcu.soft.tree;import java.util.ArrayList;import java.util.Collections;import java.util.List;/*哈夫曼树的实现类*/public class HuffmanTree {private List<Node> list = new ArrayList<Node>();// 构造哈夫曼树@SuppressWarnings("unchecked")public void createTree(int a[]) {// 初始化结点Node node;for (int i = 0; i < a.length; i++) {node = new Node(a[i]);list.add(node);}Collections.sort(list, new WeightComparator());// 将list里最小的两个结点合并for (int n = a.length; n>1; n--) {node = new Node(list.get(0).getWeight() + list.get(1).getWeight(),null, list.get(0), list.get(1));list.remove(0);//移除先前index为0的结点list.remove(0);//移除先前index为1的结点list.add(node);//添加新生成的结点Collections.sort(list, new WeightComparator());//重新排序}node=list.get(0);//获取哈夫曼树的根结点System.out.println("打印所有结点");preOrder(node);//前序遍历哈夫曼树}public void preOrder(Node root) { // -------------------1.递归 if (root == null) { return; } else { System.out.print(root.getWeight() + " ");// 输出结点的数据域 preOrder(root.getLeft()); // 遍历左子树 preOrder(root.getRight());//遍历右子树 }}}

总结：虽然实现了哈夫曼树，但是感觉这种实现的方法的代价很大。每一次通过两个最小的权值获得新的权值后，每一次都要重新排序。待续。。。

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