Given Tree
root = Node ( 15 ) NEW_LINE root . left = Node ( 3 ) NEW_LINE root . right = Node ( 7 ) NEW_LINE root . left . left = Node ( 15 ) NEW_LINE root . left . right = Node ( 1 ) NEW_LINE root . right . left = Node ( 31 ) NEW_LINE root . right . right = Node ( 9 ) NEW_LINE