huffumancode.java

用JAVA实现哈夫曼编码

import java.io.*;
public class Huffumancode {

	/**
	 * @param args
	 */
	static float sum=0;
	static String s;
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		new Huffumancode().run();

	}
	public void run()
	{
		try
		{
			
			FileReader fr=new FileReader("WordAndFreq.txt");
			BufferedReader br=new BufferedReader(fr);
			String s=null;
			Node []A=new Node[24686];
			A[0]=new Node();
			A[0].freq=24685;
			int i=1;
			String []st=new String [2];
			while((s=br.readLine())!=null)
			{
				st=s.split("\\s");
				A[i]=new Node();
				A[i].data=st[0];
				A[i].freq=Integer.parseInt(st[1]);
				i++;
			}
			System.out.println(A[24685].data +A[24685].freq);
			heap_sort(A);
			A[0].freq=24685;
			build_huffmantree(A);
		
			System.out.println("A[1]ede pin ldu"+A[1].freq);
			
			FileWriter fw=new FileWriter("output.txt");
			BufferedWriter bw=new BufferedWriter(fw);
			preorder(A[1],bw);
			bw.flush();
			
			float average=sum/3330999;
			String s1="the average length of the code is :".concat(Float.toString(average));
			bw.write(s1);
			bw.close();
			System.out.println(average);
			
			
			
		}
		catch(Exception e)
		{
			System.out.println(e);
		}
	}
	public void min_Heapify( Node []A, int i)
	{    
		
		int l=2*i;
		int r=2*i+1;
		int small;
		if(l<=A[0].freq&&A[l].freq<A[i].freq)
			small=l;
		else small=i;
		if (r<=A[0].freq&&A[r].freq<A[small].freq)
			small=r;
		//System.out.println("haha ");
		if (small!=i)
		{
			Node node1=new Node();
			node1=A[small];
			A[small]=A[i];
			A[i]=node1;
			min_Heapify( A , small);
			
			//depth_visited(A[1]);
		}
	}
	public void build_min_heap(Node [] B)
	{
		int len=(int)B[0].freq;
		for(int j=len/2;j>0;j--)
	       min_Heapify(B,j);
	}
	public void heap_sort(Node [] b)
	{
		build_min_heap(b);
		int k=(int)b[0].freq;
		for(int i=k;i>=2;i--)
		{
			Node node1=new Node();
	        node1=b[1];b[1]=b[i];
	        b[i]=node1;
	        b[0].freq=b[0].freq-1;
	        min_Heapify(b,1);
			
		}
			
	}
	public void build_huffmantree(Node []B)
	{
	    int len=(int)B[0].freq;
	    Node node;
		while(len>1)
		{   
			//System.out.println("len 长度是:"+len);
			//System.out.println("B[len] 的频率"+B[len].freq);
			//System.out.println("B[len-1] 的频率"+B[len-1].freq);
			node=new Node();
			node.freq=B[len].freq+B[len-1].freq;
			
			
			
			node.left=B[len];
			node.right=B[len-1];
			B[len]=null;
			B[len-1]=null;
		    
			//System.out.println("node 的频率："+node.freq);
			
			
		   int k=len-2;
		   while(k>=1)
		   {
			  if(B[k].freq<node.freq)
				  B[k+1]=B[k];
			  else 
				  break;
			  k--;
			
		   }
		 
		     B[k+1]=node;
		 //System.out.println(B[k+1].freq);
		 //System.out.println(B[9].freq) ;
		  len--;
		  node=null;
		 //sort(B,len);
			
			//System.out.println(index--);
			             
		}
	}
	public void preorder(Node node , BufferedWriter bt)
	{
		if(node!=null)
		{    
			
			if(node.left!=null&&node.right!=null)
			{
				if(node.code!=null)
					node.left.code="0".concat(node.code);
				else
					node.left.code="0";
				if(node.code!=null)
					node.right.code="1".concat(node.code);
				else
					node.right.code="1";
			}
		    if(node.left==null&&node.right==null)
			{    
		    	try
		    	{
		    	  s=node.data.concat(" ");
		    	  s=s.concat(node.code);
		    	  bt.write(s);
		    	  bt.newLine();
		    	}
		    	catch(Exception e)
		    	{
		    		System.out.println(e);
		    	}
		    	//System.out.println(node.data+ " "+node.code);
				sum=sum+node.code.length()*node.freq;
			}
			
			preorder(node.left,bt);
			preorder(node.right,bt);
		}
	}

}
class Node 
{
	Node left=null;
	Node right=null;
    int freq=0;
	String data=null;
	String code=null;
	
	
}