'''
Created on Feb 5, 2019

@author: aavinash

link: https://leetcode.com/problems/unique-binary-search-trees/

'''

class Solution(object):
    def numTrees(self, n):
        """
        :type n: int
        :rtype: int
        """
        
        d={}
        
        
    def get_comb_list(self):
        pass
    
    def form_trees(self): 
        pass
    
    def form_tree_trav_string(self):
        
           
        
        
        
        
        
if __name__ == '__main__':
            