|
Displaying Source Code(s)
|
|
Using Shannon's algorithm for code assignment to characters of
varying probabilities.
--------------------------------------------------------------------------------
Description : This code gives the binary codes to each of the
characters having different probabilities of occurence,using the
Shannon's algorithm. User must enter the probabilities .Make
sure that the sum of all probablities is <= to 1. The character
with the highest probability of occurence will be assigned the
code of least length, while that of the lowest probability will
be assigned the longest length. Before the codes are assigned,
the characters are sorted in descending order. Hence, the
results displayed also are in descending order.
#include<stdio.h>
#include<conio.h>
#include<math.h>
int temp,i,j,col=0,n=100,count=0,b[10][2];
float a[10],sum=100;
char c[10][10];
void main()
{
void part(int,int);
clrscr();
printf("Enter number of characters ");
while(n>10)
{
printf("(Not more than 10) ");
scanf("%d",&n);
}
while(sum>1)
{
printf("Enter their probabilities of occurences<BR>);
sum=0;
for(i=1;i<=n;i++)
{
printf(".");
scanf("%f",&a[i]);
while(a[i]>=1)
a[i]=a[i]/10;
sum=sum+a[i];
if(sum>1)
break;
}
if(sum>1)
printf("Sum of probabilities must be less than or equal to 1
!<BR>);
}
for(i=0;i<10;i++)
{
for(j=0;j<10;j++)
c[i][j]='*';
}
for(i=0;i<n;i++)
{
for(j=0;j<n;j++)
{
if(a[j]<a[j+1])
{
temp=a[j];
a[j]=a[j+1];
a[j+1]=temp;
}}}
printf("
<BR>);
part(1,n);
printf("The codes are <BR>);
for(i=0;i<n;i++)
{
for(j=0;j<10;j++)
printf("%c ",c[i][j]);
printf("<BR>);
}
getch();
}
void part(int low,int high)
{
int min=100,k,z,sum=0,dif,sum1=0,l=0;
z=(high-low);
z=abs(z);
for(j=0;j<10;j++)
for(i=0;i<2;i++)
b[j][i]=0;
if(z>1)
{
count++;
for(i=low-1;i<high;i++)
sum=sum+a[i];
sum1=a[low-1];
sum=sum-a[low-1];
for(i=low;i<=high;i++)
{
dif=sum-sum1;
sum1=a[i]+sum1;
sum=sum-a[i];
b[l][0]=abs(dif);
b[l][1]=i;
l++;
}
for(i=0;i<l;i++)
if(min>b[i][0])
{
min=b[i][0];
k=b[i][1];
}
for(i=low-1;i<k;i++)
c[i][col]='0';
for(i=k;i<high;i++)
c[i][col]='1';
col++;
part(low,k);
part(k+1,high);
}
else
{
c[low][col]='1';
c[high][col]='0';
if(c[high+1][col]=='*'&&high<=9)
while(c[high+1][col]=='*')
col--;
col++;
}
} |
|
|
123
Eng