Enter the binary tree ... 1 / \ 2 3 / \ 4 5 \ / \ 8 6 7 / 9
root = Node ( 1 ) NEW_LINE root . left = Node ( 2 ) NEW_LINE root . right = Node ( 3 ) NEW_LINE root . left . left = Node ( 4 ) NEW_LINE root . left . right = Node ( 5 ) NEW_LINE root . left . right . left = Node ( 6 ) NEW_LINE root . left . right . right = Node ( 7 ) NEW_LINE root . left . left . right = Node ( 8 ) NEW_LINE root . left . left . right . left = Node ( 9 ) NEW_LINE diameter ( root ) NEW_LINE