Construct a Binary Tree 4 / \ 9 2 / \ \ 3 5 7
Node * root = NULL ; root = newNode ( 4 ) ; root -> left = newNode ( 9 ) ; root -> right = newNode ( 2 ) ; root -> left -> left = newNode ( 3 ) ; root -> left -> right = newNode ( 5 ) ; root -> right -> right = newNode ( 7 ) ;