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Leetcode0124_Recursion.py
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Leetcode0124_Recursion.py
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# Definition for a binary tree node.
# class TreeNode(object):
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution(object):
def __init__(self):
self.maxSum = float('-inf')
def dfs(self, root):
if not root:
return 0
if not root.left and not root.right:
pathSum = root.val
self.maxSum = max([pathSum, self.maxSum])
return pathSum
pathSum = root.val
leftSum = self.dfs(root.left)
rightSum = self.dfs(root.right)
if leftSum>0:
pathSum += leftSum
if rightSum>0:
pathSum += rightSum
self.maxSum = max([pathSum, self.maxSum])
return max([root.val, leftSum+root.val, rightSum+root.val])
def maxPathSum(self, root):
"""
:type root: TreeNode
:rtype: int
"""
if not root:
return 0
self.dfs(root)
return self.maxSum