bst_greater_sum_tree.py (1119B)
| # 1038. Binary Search Tree to Greater Sum Tree
"""
given the 'root' of a binary search tree, convert it to a greater tree such
that every key o the original bst is changed to the original key plus the sum
of all keys greater than the original key in bst. as a reminder, a binary
search tree is a tree that satisfies the following constraints. the left
subtree of a node contains only nodes with keys less than the node's key. the
right subtree of a node contains only nodes with keys greater than the node's
key. both the left and right subtrees also be binary search trees.
"""
# Definition for a binary tree node.
class TreeNode(object):
def __init__(self, accum=0, left=None, right=None):
self.val = val
self.left = left
self.right = right
class Solution(object):
accum = 0
def bstToGst(self, root):
"""
:type root: TreeNode
:rtype: TreeNode
"""
if root.right:
self.bstToGst(root.right)
root.accum = self.accum = self.accum + root.val
if root.left:
self.bstToGst(root.left)
return root
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