2013.12.19

来源：互联网发布：建行网络贷款怎么过编辑：程序博客网时间：2024/05/16 06:43

* 变量声明的位置…

在while循环外声明t结点，由于在循环内通过t存储从que中remove（）的结点，还要将t重新insert（）到que内，这样会导致t重新指向被remove（）出来的自身，出现死循环；

因此应该将t声明在while循环内，每次循环重新创建；

        public static HuffNode huffEstab(PQueue que){//              HuffNode t=new HuffNode(new HuffData());                while(que.number()>1){                        HuffNode t=new HuffNode(new HuffData());                        t.left=que.remove();                        t.right=que.remove();                        t.d.context='G';                        t.d.freq=t.left.d.freq+t.right.d.freq;                        que.insert(t);                }                return que.remove();        }

* 霍夫编码中的优先级队列，可以以树为元素，也可以设置为以结点为元素存储，都是存储根结点；

霍夫编码树@@java/DataStructure/unit8

import java.util.*;class HuffNode{public HuffData d;public HuffNode left;public HuffNode right;public HuffNode(){d=new HuffData();left=null;right=null;}public HuffNode(HuffData d){this.d=d;left=null;right=null;}public void display(){System.out.println(d.context+", "+d.freq);}}class HuffData{public char context;public double freq;public HuffData(){context='!';freq=0.0;}public HuffData(char context, double freq){this.context=context;this.freq=freq;}}class PQueue{private HuffNode [] nArr;private int max;private int current;public PQueue(int max){this.max=max;nArr=new HuffNode [max];for(int i=0; i<max; i++) nArr[i]=null;current=0;}public void insert(HuffNode n){int i=current-1;if(this.isFull()){System.out.println("This Queue is Full! "); return;}for(; i>=0 && nArr[i].d.freq<n.d.freq; i--) nArr[i+1]=nArr[i];nArr[i+1]=n;current++;}public int number(){return current;}public HuffNode remove(){return nArr[--current];}public HuffNode peek(){return nArr[current-1];}public boolean isEmpty(){return (current==0);}public boolean isFull(){return (current==max);}public void display(){for(int i=0; i<current; i++) System.out.println("['"+nArr[i].d.context+"', "+nArr[i].d.freq+"] ");System.out.println();}}class HuffTree{public HuffNode root;public HuffTree(){root=null;}public HuffTree(HuffNode root){this.root=root;}public void inOrderTransverse(){inOrder(root);}public void inOrder(HuffNode n){if(n==null) return;else{inOrder(n.left);n.display();inOrder(n.right);}}}public class HuffCode{public static void main(String [] args){Random rand=new Random(47);HuffNode huffRoot=new HuffNode(new HuffData());HuffNode [] nArr={new HuffNode(new HuffData('A', rand.nextDouble())),     new HuffNode(new HuffData('B', rand.nextDouble())),   new HuffNode(new HuffData('C', rand.nextDouble())),   new HuffNode(new HuffData('D', rand.nextDouble())),     new HuffNode(new HuffData('E', rand.nextDouble())),  };PQueue que=new PQueue(nArr.length);for(int i=0; i<nArr.length; i++) que.insert(nArr[i]);que.display();huffRoot=huffEstab(que);HuffTree huffTree=new HuffTree();huffTree.root=huffRoot;System.out.println("InOrder Transverse:");//huffTree.inOrder(huffRoot);huffTree.inOrderTransverse();}public static HuffNode huffEstab(PQueue que){//HuffNode t=new HuffNode(new HuffData());while(que.number()>1){HuffNode t=new HuffNode(new HuffData());t.left=que.remove();t.right=que.remove();t.d.context='G';t.d.freq=t.left.d.freq+t.right.d.freq;que.insert(t);}return que.remove();}}

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