2019-01-26 08:34:45 +08:00

11 lines
289 B
Python

class Solution(object):
def __init__(self):
self.prev = None
def flatten(self, root):
if not root: return None
self.flatten(root.right)
self.flatten(root.left)
root.right = self.prev
root.left = None
self.prev = root