Program for array representation of binary trees

import java.io.*;
import java.util.*;


class Nodetype
{
      int info,used;
      Nodetype(int i,int u)
  {
  info=i;
  used=u;
}
}


class Functions
{
Nodetype node[]=new Nodetype[20];
int TRUE=1,FALSE=0;
void maketree(int x)
{
int p;
node[0]=new Nodetype(x,1);
/*the tree consists of node 0 alone*/
  /*all other nodes are null nodes*/
  for(p=1;p<20;p++)
node[p]=new Nodetype(0,0);
   }/*end maketree*/


void setleft(int p,int x)
{
int q;
q=2*p+1;
/*q is the position of the left son*/
if(q>=20)
System.out.println("array overflow");
else
if(node[q].used==TRUE)
System.out.println("\nInvalid insertion");
else
{
node[q].info=x;
node[q].used=TRUE;
}/*end if*/
}/*end setleft*/


void setright(int p,int x)
    {
           int q;
           q=2*p+2;
           /*q is the position of the left son*/
           if(q>=20)
System.out.println("array overflow");
           else
if(node[q].used==TRUE)
System.out.println("\nInvalid insertion");
else
  {
node[q].info=x;
node[q].used=TRUE;
  }/*end if*/
      }/*end setright*/




void create() //throws IOException
{
String str;
int i=1,p,q,ne,number;




System.out.println("\nEnter number of elements : ");
ne=getNumber();


System.out.println("\nEnter numbers : ");
number=getNumber();
maketree(number);


while(i<ne)
{
number=getNumber();
i++;
p=q=0;
while(q < 20 && node[q].used==TRUE && number!=node[p].info)
{
p=q;
if(number<node[p].info)
q=2*p+1;
else
q=2*p+2;
}
/*if the number is in the tree it is a duplicate*/
if(number==node[p].info)
System.out.println("Sorry!!..."+number+" is a Duplicate value\n");
else
if (number<node[p].info)
setleft(p,number);
else
setright(p,number);
}
}/*end create*/


int getNumber()
{
String str;
int ne=0;
InputStreamReader input=new InputStreamReader(System.in);
BufferedReader in=new BufferedReader(input);
try
{
str=in.readLine();
ne=Integer.parseInt(str);
}
catch(Exception e)
{
System.out.println("I/O Error");
}
return ne;
}/*end getNumber*/


}


class BST
{
public static void main(String args[])//hrows IOException, NullPointerException
{


Functions f=new Functions();
f.create();
}
}




/*
Enter number of nodes : 10


Enter info 10 nodes :
50
1
70
33
50
Sorry !.....50is a duplicate


1
Sorry !.....1is a duplicate


57
80
33
Sorry !.....33is a duplicate


22
*//