/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
class Solution {
    public List<TreeNode> allPossibleFBT(int n) {
        if ((n & 1) == 0) {
            return Collections.emptyList();
        }
        List[] arr = new ArrayList[n + 1];
        arr[1] = new ArrayList<>(1);
        arr[1].add(new TreeNode(0));
        for (int i = 3; i <= n; i = i + 2) {
            List<TreeNode> list = new ArrayList<>();
            arr[i] = list;
            for (int j = 1; j < i; j = j + 2) {
                for (TreeNode right : (List<TreeNode>) arr[i - j - 1]) {
                    for (TreeNode left : (List<TreeNode>) arr[j]) {
                        TreeNode node = new TreeNode(0);
                        node.right = right;
                        node.left = left;
                        list.add(node);
                    }
                }
            }
        }
        return arr[n];
    }
}