Driver Code
root = Node ( 10 ) NEW_LINE root . left = Node ( 20 ) NEW_LINE root . right = Node ( 30 ) NEW_LINE root . left . left = Node ( 40 ) NEW_LINE root . left . left . left = Node ( 70 ) NEW_LINE root . left . right = Node ( 50 ) NEW_LINE root . right . left = Node ( 60 ) NEW_LINE root . left . left . right = Node ( 80 ) NEW_LINE preorderIterative ( root ) NEW_LINE