现代信息检索作业5——2

#include<iostream>
#include<stdio.h>

using namespace std;

typedef unsigned char Bit;

class BitStream{
public:
	unsigned char* bitstream;
	int position; 
	int start;
	BitStream()
	{
		start = 0;
		position = 0;
		bitstream = new unsigned char[1000];
		for(int i=0;i<1000;i++)bitstream[i]=0;
	}
	~BitStream()
	{
		delete[] bitstream;
	}
	void Add(Bit tmp)
	{
		int x = position / 8;
		int y = 7 - (position % 8);
		bitstream[x] = bitstream[x] | (tmp<<y);
		position++;
	}
	Bit Pop()
	{
		int x = start / 8;
		int y = 7 - (start % 8);
		start++;
		return (bitstream[x]>>y)&0x1;
	}
	bool IsEnd()
	{
		return start==position;
	}
	void Print()
	{
		int n,h,sb=position;
		if(position%8==0)n=position/8;
		else n=position/8+1;

		for(int i=0;i<n;i++)
		{
			Bit tmp = bitstream[i];
			if(sb>=8)h=0;
			else h=8-sb;
			for(int j=7;j>=h;j--)
			{
				int n = (((int)tmp)>>j) &0x1;
				printf("%d",n);
			}
			sb-=8;
			printf(" ");
		}
		printf("\n");
	}
};

BitStream* GammaEncode(int numbers[],int length)
{
	BitStream* bs = new BitStream();
	for(int i=0;i<length;i++)
	{
		int n = numbers[i];
		int count = 31;

		if(n==0){cout<<"can not be 0"<<endl;return bs;}

		while(!(n&0x80000000)){count--;n=n<<1;}

		//长度部分
		for(int j=0;j<count;j++)
			bs->Add(1);
		bs->Add(0);

		//偏移部分
		for(int j=1;j<=count;j++)
		{
			Bit tmp = ((n<<j)>>31)&0x1;
			bs->Add(tmp);
		}
	}

	return bs;
}

int* GammaDecode(BitStream* bs,int &length)
{
	int* a = new int[100];
	while(!bs->IsEnd())
	{
		int count = 0;
		while(bs->Pop())count++;

		int n=1;
		for(int i=0;i<count;i++)
			n = (n<<1)|(bs->Pop());

		a[length++] = n;
	}
	return a;
}
int main()
{
	int a[] = {1,2,3,4,9,13,24,511,1025};
	//int a[] = {9};
	BitStream* hehe =  GammaEncode(a,9);
	hehe->Print();

	int length = 0;
	int* b;
	b=GammaDecode(hehe,length);
	for(int i=0;i<length;i++)
		cout<<b[i]<<endl;
	system("pause");
	return 0;
}