124.binary-tree-maximum-path-sum.py

#
# @lc app=leetcode id=124 lang=python3
#
# [124] Binary Tree Maximum Path Sum
#


# Difficulty: Hard
# Frequency: 67.0%
# Tags: Dynamic Programming, Tree, Depth-First Search, Binary Tree
# URL: https://leetcode.com/problems/binary-tree-maximum-path-sum/
#
# --- Problem Description ---
#
# 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.
#
#
#
# Example 1:
#
# Input: root = [1,2,3]
# Output: 6
# Explanation: The optimal path is 2 -> 1 -> 3 with a path sum of 2 + 1 + 3 =
# 6.
#
# Example 2:
#
# 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.
#
#
#
# Constraints:
#
# 	  - The number of nodes in the tree is in the range [1, 3 * 10^(4)].
# 	  - -1000 <= Node.val <= 1000
#

#
# --- Community Solutions ---
#
# https://leetcode.com/problems/binary-tree-maximum-path-sum/solutions
#

# @lc code=start
# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def maxPathSum(self, root: Optional[TreeNode]) -> int:
        

# @lc code=end