java實現 Elias Gamma 編碼算法

Elias Gamma編碼步驟：

1、將n轉換成他的二進制形式並轉換成字符串的形式

2,、如果n的而今只需要m個bit來表示，將m-1，然後再轉換的字符串前面添加m-1個0

算法設計如下：

package test;

import java.util.ArrayList;
import java.util.Scanner;

public class Elias {
	public String eliasGammaEncode(int n)
	{
		String s=intToBinaryString(n);
		s=addHeadZeros(s);
		return s;
	}
	public String intToBinaryString(int n){
		String s="";
		while(n>0){
			if((n&1)==0){
				s="0"+s;
			}
			else{
				s="1"+s;
			}
			n=n>>1;
		}
		return s;
	}
	public ArrayList<Integer> eliasGammaDecodToArray(String s){
		ArrayList<Integer>  list= new ArrayList<Integer>();
		while(s.length()>0){
			int n=eliasGammaDecode(s);
			list.add(n);
			s=s.substring(eliasGammaEncode(n).length());
		}
		return list;
	} 
	public int eliasGammaDecode(String s){
		int len=getHeadZerosCount(s);
		if(len<=0){
			throw new IllegalArgumentException("illegal length");
		}
		s = s.substring(len);
		String binary =s.substring(0,len+1);
		int n=binaryStringToInt(binary);
		return n;
	}
	public int getHeadZerosCount(String s)
	{
		//自行解決
		int n=0;
		return n;
	}
	public int binaryStringToInt(String binary){
	//自行解決
		int n=0;
		return 0;
	}
	public String addHeadZeros(String s){
		int n=s.length();
		String s1=s;
		for(int i=0;i<n-1;i++){
			s1="0"+s1;
		}
		return s1;
		
	}
	
	
	public static void main(String args[]){
		Elias e=new Elias();
		Scanner sc =new Scanner(System.in);
		int n=sc.nextInt();
		//編碼
		System.out.println(e.eliasGammaEncode(n));
		//解碼
		System.out.println(e.eliasGammaDecode(e.eliasGammaEncode(n)));
		
	}

}