Question Discussion & Solution

a)

public void preOrder(Tree root) 
{   
        if (root == null) return;
 Stack stk = new Stack();
        st.add(root);        
 while (!stk.empty()) 
        {
            Tree node = stk.pop();           
            System.out.print(node.data + " ");
   if (node.left != null) stk.push(node.left);
            if (node.right != null) stk.push(node.right);
        }
}

b)

public void preOrder(Tree root) 
{   
        if (root == null) return;
  Stack stk = new Stack();      
 while (!stk.empty()) 
        {
            Tree node = stk.pop();           
            System.out.print(node.data + " ");
            if (node.right != null) stk.push(node.right);
            if (node.left != null) stk.push(node.left);
        }
}

c)

public void preOrder(Tree root) 
{   
        if (root == null) return;
 Stack stk = new Stack();
        st.add(root);        
 while (!stk.empty()) 
        {
            Tree node = stk.pop();           
            System.out.print(node.data + " ");
            if (node.right != null) stk.push(node.right);
            if (node.left != null) stk.push(node.left);
        }
}

d) None of the mentioned