算术编码.cpp

里面包括： 哈夫曼编码

#include <iostream>
#define M 100
#define N 4
using namespace std;
class suanshu
{ 
 int count,length;
 char number[N],n;
 long double chance[N],c;
 char code[M];
 long double High,Low,high,low,d;
public:
 suanshu()
  {High=0;Low=0;}
 void get_number();
 void get_code();
 void coding();
 ~suanshu(){}
};

void suanshu::get_number()
{int i;
 cout<<"please input the number and its chance."<<endl;
 for(int i=0;i<N;i++)
 {
  cin>>n>>c;
  number[i]=n;
  chance[i]=c;
 }
 if(i==20) {cout<<"the number is full."<<endl;}
 //else 
 count=i;
}

void suanshu::get_code()
{
 cout<<"please input the code's length:";
 cin>>length;
 while(length>=M)
 {
  cout<<"the length is too larger,please input a smaller one.";
  cin>>length;
 }
 for(int i=0;i<length;i++)
 {
  cin>>code[i];
 }
}

void suanshu::coding()
{
 int i,j=0;
 for(i=0;i<count;i++)
  if(code[0]==number[i]) break;
 while(j<i)
  Low+=chance[j++];
 d=chance[j];
 High=Low+d;
 for(i=1;i<length;i++)
  for(j=0;j<count;j++)
  {
   if(code[i]==number[j])
   {
    if(j==0)
    {
     low=Low;
     high=Low+chance[j]*d;
     High=high;
     d*=chance[j];
    }
    else
    {
     float chance_l=0.0;
     for(int k=0;k<=j-1;k++)
      chance_l+=chance[k];
     low=Low+d*chance_l;
     high=Low+d*(chance_l+chance[j]);
     Low=low;
     High=high;
     d*=chance[j];
    }
   }
   else continue;
  }
 cout<<"the result is:"<<Low<<endl;
}

int main()
{
 suanshu a;
 a.get_number();
 a.get_code();
 a.coding();
 return 0;
}