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);}}}