#include
#include
#include

class node
{
public:
class node *left;
class node *right;
int data;
};

class tree: public node
{
public:
int stk[50],top;
node *root;
tree()
{
root=NULL;
top=0;
}
void insert(int ch)
{
	node *temp,*temp1;
	if(root== NULL)
	{
		root=new node;
		root->data=ch;
		root->left=NULL;
		root->right=NULL;
		return;
	}
	temp1=new node;
	temp1->data=ch;
	temp1->right=temp1->left=NULL;
	temp=search(root,ch);
	if(temp->data>ch)
		temp->left=temp1;
	else
		temp->right=temp1;

}
node *search(node *temp,int ch)
{
	if(root== NULL)
	{
		cout <<"no node present";
		return NULL;
	}
	if(temp->left==NULL && temp->right== NULL)
		return temp;

	if(temp->data>ch)
	     {  if(temp->left==NULL) return temp;
		search(temp->left,ch);}
	else
	      { if(temp->right==NULL) return temp;
	      search(temp->right,ch);

}              }

void display(node *temp)
{
	if(temp==NULL)
	 return ;
	display(temp->left);
       cout<data << " ";
	display(temp->right);
}
void postorder( node *root)
{
	node *p;
	p=root;
	top=0;

	while(1)
	{
	while(p!=NULL)
	{
		stk[top]=p->data;
		top++;
		if(p->right!=NULL)
			stk[top++]=-p->right->data;
		p=p->left; 
	}
	while(stk[top-1] > 0 || top==0)
	{
	   if(top==0) return;
	   cout << stk[top-1] <<" ";
	   p=pop(root);
	}
	if(stk[top-1]<0)
	{
	  stk[top-1]=-stk[top-1];
	  p=pop(root);
      }	}

}
node * pop(node *p)
{
int ch;
ch=stk[top-1];
if(p->data==ch)
{
top--;
return p;
}
if(p->data>ch)
pop(p->left);
else
pop(p->right);
}
};
void main()
{
	tree t1;
	int ch,n,i;
	clrscr();
	while(1)
	{
		cout <<"\n1.INSERT\n2.DISPLAY 3.POSTORDER TRAVERSE\n4.EXIT\nEnter your choice:";
		cin >> ch;
		switch(ch)
		{
		case 1:   cout <<"enter no of elements to insert:";
			  cout<<"\n enter the elements";
			  cin >> n;
			  for(i=1;i<=n;i++)
			  {  cin >> ch;
			     t1.insert(ch);
			  }
			   break;
		case 2:   t1.display(t1.root);break;
		case 3:   t1.postorder(t1.root); break;
		case 4:   exit(1);
		}
	}
}

OUTPUT

1.INSERT
2.DISPLAY 3.POSTORDER TRAVERSE
4.EXIT
Enter your choice:1
enter no of elements to insert:
enter the elements7
5 24 36 11 44 2 21

1.INSERT
2.DISPLAY 3.POSTORDER TRAVERSE
4.EXIT
Enter your choice:2
2 5 11 21 24 36 44

1.INSERT
2.DISPLAY 3.POSTORDER TRAVERSE
4.EXIT
Enter your choice:3
2 21 11 44 36 24 5

1.INSERT
2.DISPLAY 3.POSTORDER TRAVERSE
4.EXIT
Enter your choice:4

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