LeetCode 938.二叉搜索树的范围和（简单）

pyhton 前序遍历

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def rangeSumBST(self, root: Optional[TreeNode], low: int, high: int) -> int:
        self.count = 0
        if root==None:
            return None
        
        self.inorder(root,low,high)

        return self.count

    def inorder(self,root,low,high):
        p = root
        if p==None:
            return
        if(p.val>=low and p.val<=high):
           self.count +=p.val
        self.inorder(p.left,low,high)
        self.inorder(p.right,low,high)