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 ) ;