Solving Unique Binary Search Trees II in go. Please try yourself first to solve the problem and submit your implementation to LeetCode before looking into solution.

Problem Description

Example:

Input: 3
Output:
[
  [1,null,3,2],
  [3,2,null,1],
  [3,1,null,null,2],
  [2,1,3],
  [1,null,2,null,3]
]
Explanation:
The above output corresponds to the 5 unique BST's shown below:

   1         3     3      2      1
    \       /     /      / \      \
     3     2     1      1   3      2
    /     /       \                 \
   2     1         2                 3

See the full details of the problem Unique Binary Search Trees II at LeetCode

Originally posted at: @github.com/halfrost/LeetCode-Go