full binary tree is a binary tree where each node has exactly 0 or 2 children.
Return a list of all possible full binary trees with
N nodes. Each element of the answer is the root node of one possible tree.
node of each tree in the answer must have node.Val = 0.
You may return the final list of trees in any order.
Input: 7 Output: [[0,0,0,null,null,0,0,null,null,0,0],[0,0,0,null,null,0,0,0,0],[0,0,0,0,0,0,0],[0,0,0,0,0,null,null,null,null,0,0],[0,0,0,0,0,null,null,0,0]] Explanation:
- 1 <= N <= 20