A path in a binary tree is a sequence of nodes where each pair of adjacent nodes in the sequence has an edge connecting them. A node can only appear in the sequence at most once. Note that the path does not need to pass through the root.
The path sum of a path is the sum of the node's values in the path.
Given the root
of a binary tree, return the maximum path sum of any non-empty path.
Input: root = [-10,9,20,null,null,15,7] Output: 42 Explanation: The optimal path is 15 -> 20 -> 7 with a path sum of 15 + 20 + 7 = 42.
class Solution:
def maxPathSum(self, root: Optional[TreeNode]) -> int:
ans = [root.val]
#max w/o split
def dfs(root):
if not root :
return 0
ml = dfs(root.left)
ml = max(ml, 0)
mr = dfs(root.right)
mr = max(mr, 0)
#max with split
ans[0] = max(ans[0], root.val + ml + mr)
return root.val + max(ml, mr)
dfs(root)
return ans[0]
Explaination :
Comments
Post a Comment