Huffman Tree Algorithm (Simple)

#include<conio.h>
#include <stdio.h>
#define max 0
#define mxbits 20

struct ele
{
  int posn;
  int info;
  int code[mxbits];
  int lft;
  int rgt;
}ar[max],tr[max],item,item1,tmp1,tmp2,tmp3;

int noe,i,j,ptr,par,ind,left,right;

void ins_heap(int n,struct ele item)
{
 tr[n] = item;
 if(n != 1)
 {
 ptr = n;
 par = ptr/2;
 while(ptr>1 && tr[par].info > tr[ptr].info)
 {
  item = tr[par];
  tr[par] = tr[ptr];
  tr[ptr] = item;
  ptr = par;
  par = ptr/2;
 }
 }
}

void inp_dat()
{
 do
 {
 printf("\n\n Enter the no. of elements : ");
 scanf("%d",&noe);
 }while(noe<=0 || noe>=max/2);
 printf("\n\n Enter the frequencies '%d' elements : ",noe);
 for(i=1;i<=noe;i++)
  {
  scanf("%d",&ar[i].info);
  ar[i].posn = i;
  ar[i].lft = 0;
  ar[i].rgt = 0;
  ins_heap(i,ar[i]);
  }
}


struct ele del_heap(int end)
{
 item1 = tr[1];
 tr[1] = tr[end];
 par = 1; left = 2; right = 3;
 ind = 0;
 while(par < end && ind == 0)
 {
  if(tr[left].info < tr[par].info && tr[left].info < tr[right].info && left<end)
  {
  item = tr[left];
  tr[left] = tr[par];
  tr[par] = item;
  par = left;
  }
  else if(tr[right].info < tr[par].info && tr[left].info > tr[right].info  && right<end)
  {
  item = tr[right];
  tr[right] = tr[par];
  tr[par] = item;
  par = right;
  }
  else
   ind = 1;
  left = 2*par;
  right = 2*par+1;
 }
 return item1;
}

void hfmn_tree()
{
 i = noe;
 j = i+1;
 while(i>1)
 {
  tmp1 = del_heap(i);
  tmp2 = del_heap(--i);
  tmp3.info = tmp1.info + tmp2.info;
  tmp3.posn = j;
  tmp3.lft = tmp1.posn;
  tmp3.rgt = tmp2.posn;
  ar[j] = tmp3;
  ins_heap(i,tmp3);
  j++;
 }
 ar[j-1].posn = 1;
 i = j-1;
 while(i > noe)
 {
  ar[ar[i].lft].posn = 2*ar[i].posn;
  ar[ar[i].rgt].posn = 2*ar[i].posn+1;
  i--;
 }
}

void codes()
{
  int k;
  char ch;
  printf("\n The Codes for every input is : ");
  for(i=1;i<=noe;i++)
  {
   k = 0;
   ch = 64+i;
   printf(" \n For %c : %d. ",ch,ar[i].info);
   while(ar[i].posn > 1)
   {
   ar[i].code[k] = ar[i].posn % 2;
   ar[i].posn /= 2;
   k++;
   }
   for(j=k-1;j>=0;j--)
    printf("%d",ar[i].code[j]);
  }
}

void main()
{
clrscr();
inp_dat();
hfmn_tree();
codes();
getch();
}