2013.12.20

//对字符串进行操作的时候，要考虑大小写；
//霍夫曼编码，把待编码文本赋值给str，便可输出对字母以及空格“，”字符的编码
public class HuffCode{
	public static void main(String [] args){
		Random rand=new Random(47);
		HuffNode huffRoot=new HuffNode(new HuffData());
		double [] dArr=new double [28];
		HuffNode [] nArr=new HuffNode [28];
//		String str="Hello my name is ShangYunlei my girl friend is YiMing";
//		String str="In the traffic court of a large mid-western city, a young lady was brought before the judge to answer a ticket given her for driving through a red light. She explained to his honor that she was a school teacher and requested an immediate disposal of her case in order that she might hasten on to her classes. A wild gleam came into the judge's eye. You are a school teacher, eh? said he. Madam, I shall realize my lifelong ambition. Sit down at that table and write I went through a red light five hundred times.";
		String str="abcdefghijklmnopqrstuvwxyz ,";
		System.out.println(str.length());
//计算文本中字母（忽略大小写）， “ ”， “，” 出现的概率
		dArr=frequencyCalculate(str);
//用HuffNode将字符与其出现的概率联系起来
		for(int i=0; i<dArr.length-2; i++){
			nArr[i]=new HuffNode(new HuffData((char)('A'+i), dArr[i]));
		}
		nArr[nArr.length-2]=new HuffNode(new HuffData(' ', dArr[dArr.length-2]));
		nArr[nArr.length-1]=new HuffNode(new HuffData(',', dArr[dArr.length-1]));
//通过优先级队列建立霍夫曼树
		for(int i=0; i<dArr.length; i++) nArr[i].display();
		PQueue que=new PQueue(nArr.length);
		for(int i=0; i<nArr.length; i++) que.insert(nArr[i]);
		que.display();
		huffRoot=huffEstab(que);
//利用双栈逐层遍历法逐层遍历霍夫曼树，对相应的字符进行编码（left：0， right：1）
		HuffTree huffTree=new HuffTree();
		huffTree.root=huffRoot;
		System.out.println("InOrder Transverse:");
		huffTable(huffTree);
//以String [] 形式保存字符对应的编码
		System.out.println("HuffTable");
		String [] sArr=new String[28];
		huffTree.inOrderTransverse(sArr);
		for(int i=0; i<sArr.length-2; i++) System.out.println((char)('A'+i)+" has been coded: "+sArr[i]);
		System.out.println("  has been coded: "+sArr[26]);
		System.out.println(", has been coded: "+sArr[27]);
//遍历文本进行编码
		String oString=new String();
		for(int i=0; i<str.length(); i++){
			if(str.charAt(i)>='A' && str.charAt(i)<='Z') oString+=sArr[str.charAt(i)-'A'];
			else if(str.charAt(i)>='a' && str.charAt(i)<='z') oString+=sArr[str.charAt(i)-'a'];
			else if(str.charAt(i)==',') oString+=sArr[27];
			else if(str.charAt(i)==' ') oString+=sArr[26];
		}
		System.out.println(oString);
	}

	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='!';
			t.d.freq=t.left.d.freq+t.right.d.freq;
			que.insert(t);
		}
		return que.remove();
	}

	public static void huffTable(HuffTree tree){
		HuffStack cStack=new HuffStack(100);
		HuffStack pStack=new HuffStack(100);
		boolean flag=true;
		tree.root.left.d.code="0";
		tree.root.right.d.code="1";
		cStack.push(tree.root.left);
		cStack.push(tree.root.right);
		while(flag){
			flag=false;
			while(!cStack.isEmpty()){
				pStack.push(cStack.pop());
			}
			while(!pStack.isEmpty()){
				HuffNode node=pStack.pop();
				node.left.d.code=node.d.code;
				node.right.d.code=node.d.code;
				node.left.d.code+="0";
				if(node.left.d.context=='!'){
					cStack.push(node.left);
					flag=true;
				}
				node.right.d.code+="1";
				if(node.right.d.context=='!'){
					cStack.push(node.right);
					flag=true;
				}
			} 
		}

	}

	public static double [] frequencyCalculate(String str){
		int [] iArr=new int [28];
		double [] dArr=new double[28];
		for(int i=0; i<str.length(); i++){
			if(str.charAt(i)==' ') iArr[26]++;
			else if(str.charAt(i)==',') iArr[27]++;
			else if(str.charAt(i)>='A' && str.charAt(i)<='Z') iArr[str.charAt(i)-'A']++;
			else if(str.charAt(i)>='a' && str.charAt(i)<='z') iArr[str.charAt(i)-'a']++;
		}
		int sum=0;
		for(int i=0; i<iArr.length; i++) sum+=iArr[i];
		for(int i=0; i<iArr.length; i++) dArr[i]=(double)iArr[i]/(double)sum;
		return dArr;
	}
}

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+", "+d.code);
	}
}

class HuffData{
	public char context;
	public double freq;
	public String code;

	public HuffData(){
		context='!';
		freq=0.0;
		code=null;
	}

	public HuffData(char context, double freq){
		this.context=context;
		this.freq=freq;
		code=null;
	}
}

class HuffStack{
	private HuffNode [] nArr;
	private int max, current;

	public HuffStack(){
		nArr=null;
		max=0;
		current=0;
	}

	public HuffStack(int max){
		this.max=max;
		nArr=new HuffNode[max];
		for(int i=0; i<max; i++) nArr[i++]=new HuffNode();
		current=0;
	}

	public void push(HuffNode node){
		if(this.isFull()) System.out.println("The Stack is Full. ");
		else nArr[current++]=node;
	}

	public HuffNode pop(){
		return nArr[--current];
	}

	public int depth(){
		return current;
	}

	public HuffNode peek(){
		return nArr[current-1];
	}

	public boolean isEmpty(){
		return current==0;
	}

	public boolean isFull(){
		return current==max;
	}
}

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(String [] sArr){
		inOrder(root, sArr);
	}

	public void inOrder(HuffNode n, String [] sArr){
		if(n==null) return;
		else{
			inOrder(n.left, sArr);
			if(n.d.context!='!'){
				if(n.d.context>='A' && n.d.context<='Z') sArr[n.d.context-'A']=n.d.code;
				else if(n.d.context==' ') sArr[26]=n.d.code;
				else if(n.d.context==',') sArr[27]=n.d.code;
			}
			inOrder(n.right, sArr);
		}
	}

}