Binary Tree Maximum Path Sum
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:
![](https://assets.leetcode.com/uploads/2020/10/13/exx1.jpg)
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:
![](https://assets.leetcode.com/uploads/2020/10/13/exx2.jpg)
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 * 104]
. -1000 <= Node.val <= 1000
Solution(javascript)
/**
* Definition for a binary tree node.
* function TreeNode(val, left, right) {
* this.val = (val===undefined ? 0 : val)
* this.left = (left===undefined ? null : left)
* this.right = (right===undefined ? null : right)
* }
*/
/**
* @param {TreeNode} root
* @return {number}
*/
var maxPathSum = function(root) {
let maxsum=-Infinity;
function findmaxsum(node){
if(node === null) return 0;
const leftsum=findmaxsum(node.left);
const rightsum=findmaxsum(node.right);
maxsum=Math.max(maxsum, (node.val + leftsum + rightsum), node.val, node.val + Math.max(leftsum, rightsum));
return Math.max(node.val, node.val+ Math.max(leftsum, rightsum));
}
findmaxsum(root)
return maxsum;
};