[리트코드 leetcode] 1038. Binary Search Tree to Greater Sum Tree

leetcode.com/problems/binary-search-tree-to-greater-sum-tree/

Binary Search Tree to Greater Sum Tree - LeetCode

 

# 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:
    sum =0
    def bstToGst(self, root: TreeNode) -> TreeNode:
        
        def recur(node):
            if not node:
                return 
            
            node.right = recur(node.right)
            
            self.sum += node.val
            node.val = self.sum
            
            node.left = recur(node.left)
            
            return node
        
        return recur(root)