Given an integer n, return a list of all possible full binary trees with n nodes. Each node of each tree in the answer must have Node.val == 0. Each element of the answer is the root node of one possible tree. You may return the final list of trees in any order. A full binary tree is a binary tree where each node has exactly 0 or 2 children.
Input Format
Integer n
Output Format
List of treenode type
Constraints
1 <= n <= 20
Notice
NA
Example
Input
Output