leetcode1038

class Solution:
    def __init__(self):
        self.L = list()

    def inOrder(self,node):
        if node!=None:
            if node.left != None:
                self.inOrder(node.left)

            self.L.append(node)

            if node.right != None:
                self.inOrder(node.right)

    def bstToGst(self, root: TreeNode) -> TreeNode:
        self.inOrder(root)
        sums = 0
        for i in range(len(self.L)-1,-1,-1):
            sums += self.L[i].val
            self.L[i].val = sums

        return root