- A linked list is formed from the objects of the class
**Node**. The class structure of the Node is given below:`class Node{ int num; Node next; }`

Write an algorithm or a method to find and display the sum of even integers from an existing linked list.

The method declaration is as follows:

`void sumEvenNode(Node str)`

`void sumEvenNode(Node str){ if(str == null) return 0; else if(str.num % 2 == 0) return str.num + sumEvenNode(str.next); else return 0 + sumEvenNode(str.next);`

- Answer the following questions from the diagram of a binary tree given below:

**Write the pre-order traversal of the above tree structure.**

A –> E –> G –> I –> C –> H –> B –> D –> F**State the size of the tree.**

The size of the tree is 4.**Name the siblings of the nodes E and G.**

Sibling of E is B.

Sibling of G is C.