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hyer0705.ts
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37 lines (29 loc) · 987 Bytes
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/**
* Definition for a binary tree node.
* class TreeNode {
* val: number
* left: TreeNode | null
* right: TreeNode | null
* constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
* this.val = (val===undefined ? 0 : val)
* this.left = (left===undefined ? null : left)
* this.right = (right===undefined ? null : right)
* }
* }
*/
// Time Complexity: O(n)
// Space Complexity: O(h) where h is the height of the tree
function maxPathSum(root: TreeNode | null): number {
let maximumSum = -Infinity;
const dfs = (node: TreeNode | null) => {
if (!node) return 0;
let leftResult = dfs(node.left);
let rightResult = dfs(node.right);
leftResult = Math.max(0, leftResult);
rightResult = Math.max(0, rightResult);
maximumSum = Math.max(maximumSum, node.val + leftResult + rightResult);
return node.val + Math.max(leftResult, rightResult);
};
dfs(root);
return maximumSum;
}