11、创建Huffman树，生成Huffman编码 

  1 package ren.laughing.datastructure.baseImpl;
  2 
  3 import ren.laughing.datastructure.base.List;
  4 
  5 /**
  6  * 创建Huffman树
  7  * 生成Huffman编码
  8  * @author Laughing_Lz
  9  * @time 2016年4月14日
 10  */
 11 public class HuffmanTree {
 12     /**
 13      * 创建Huffman树
 14      * @param nodes
 15      * @return
 16      */
 17     public HuffmanTreeNode buildHuffmanTree(HuffmanTreeNode[] nodes){
 18         int n = nodes.length;
 19         if(n < 2){
 20             return nodes[0];
 21         }
 22         List list = new ArrayList();
 23         for(int i = 0;i<nodes.length;i++){
 24             insertList(list,nodes[i]);//按照nodes的weight从大到小顺序存入list中
 25         }
 26         for(int i = 1;i<n;i++){//选择 weight 最小的两棵树合并，循环 n-1 次
 27             HuffmanTreeNode minNode1 = (HuffmanTreeNode) list.remove(list.getSize()-1);
 28             HuffmanTreeNode minNode2 = (HuffmanTreeNode) list.remove(list.getSize()-1);
 29             HuffmanTreeNode newNode = new HuffmanTreeNode(minNode1.getWeight()+minNode2.getWeight(), "root");
 30             newNode.setLChild(minNode1);
 31             newNode.setRChild(minNode2);
 32             insertList(list, newNode);//重新插入list中
 33         }
 34         return (HuffmanTreeNode) list.get(0);
 35     }
 36     /**
 37      * 将huffmanTreeNode按weight从大到小存入list中
 38      * @param list
 39      * @param huffmanTreeNode
 40      */
 41     private void insertList(List list, HuffmanTreeNode node) {
 42         for(int i = 0;i<list.getSize();i++){
 43             if(node.getWeight()>((HuffmanTreeNode)list.get(i)).getWeight()){//★
 44                 list.insert(i, node);
 45                 return;
 46             }
 47         }
 48         list.insert(list.getSize(), node);//若node的weight最小，放在list最后
 49         return;
 50     }
 51     /**
 52      * 生成Huffman编码
 53      * @param root
 54      */
 55     public void generateHuffmanCode(HuffmanTreeNode root){
 56         if(root == null){
 57             return;
 58         }
 59         if(root.hasParent()){
 60             if(root.isLChild()){
 61                 root.setCoding(root.getParent().getCoding()+"0");
 62             }
 63             if(root.isRChild()){
 64                 root.setCoding(root.getParent().getCoding()+"1");
 65             }
 66         }
 67         generateHuffmanCode(root.getLChild());
 68         generateHuffmanCode(root.getRChild());
 69     }
 70     public static void main(String[] args) {
 71         HuffmanTreeNode[] nodes = creatHuffmanNodes();
 72         HuffmanTree huffmanTree = new HuffmanTree();
 73         HuffmanTreeNode root = huffmanTree.buildHuffmanTree(nodes);
 74         System.out.println("构建的Huffman树根结点是"+root.getData()+",高度为："+root.getHeight()+",权值为："+root.getWeight());
 75         huffmanTree.generateHuffmanCode(root);
 76         System.out.println(root.getRChild().getRChild().getLChild().getCoding());//★Huffman编码针对叶子结点，root结点无编码
 77     }
 78     /**
 79      * 创建HuffmanNode结点组合
 80      * @return
 81      */
 82     public static HuffmanTreeNode[] creatHuffmanNodes(){
 83         HuffmanTreeNode[] nodes = new HuffmanTreeNode[7];
 84         HuffmanTreeNode node1 = new HuffmanTreeNode(1, 'A');
 85         HuffmanTreeNode node2 = new HuffmanTreeNode(2, 'B');
 86         HuffmanTreeNode node3 = new HuffmanTreeNode(3, 'C');
 87         HuffmanTreeNode node4 = new HuffmanTreeNode(4, 'D');
 88         HuffmanTreeNode node5 = new HuffmanTreeNode(5, 'E');
 89         HuffmanTreeNode node6 = new HuffmanTreeNode(6, 'F');
 90         HuffmanTreeNode node7 = new HuffmanTreeNode(7, 'G');
 91         nodes[0] = node2;
 92         nodes[1] = node5;
 93         nodes[2] = node1;
 94         nodes[3] = node3;
 95         nodes[4] = node4;
 96         nodes[5] = node7;
 97         nodes[6] = node6;
 98         return nodes;
 99     }
100 }

 

posted @ 2016-04-14 17:51  回看欧洲  阅读(344)  评论(0)  编辑  收藏  举报