leetcode1008

 class Solution:
     def __init__(self):
         self.root = None

     def construct(self,order,root,i):
         if i==len(order):
             return None
         else:
             if self.root==None:
                 self.root = TreeNode(order[i])
                 self.construct(order,self.root,i+1)
             else:
                 if order[i]<root.val:
                     if root.left==None:
                         root.left = TreeNode(order[i])
                         self.construct(order,self.root,i+1)
                     else:
                         self.construct(order,root.left,i)
                 else:
                     if root.right==None:
                         root.right = TreeNode(order[i])
                         self.construct(order,self.root,i+1)
                     else:
                         self.construct(order,root.right,i)

     def bstFromPreorder(self, preorder: 'List[int]') -> 'TreeNode':
         self.construct(preorder,self.root,0)
         return self.root

比较简单的题目，递归方式构造二叉搜索树。