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$ curl repovive.com/roadmaps/graph-theory/subtree-dp/maximum-path-sum-implementation

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$ curl repovive.com/roadmaps/graph-theory/subtree-dp/maximum-path-sum-implementation

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LeetCode 124 Binary Tree Maximum Path Sum - Implementation - Subtree DP | Graph Theory | Repovive

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Graph Theory37 sections · 1633 units81h total

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LeetCode 124 Binary Tree Maximum Path Sum - Implementation

Code with global variable

Pseudocode:

maxPath := -infinity

function dfs(v)
    if v is null then
        return 0
    leftMax := max(dfs(v.left), 0)
    rightMax := max(dfs(v.right), 0)
    maxPath := max(maxPath, v.val + leftMax + rightMax)
    return v.val + max(leftMax, rightMax)

Call dfs(root), then return maxPath. Time: $O(n)$ (visit each node once). Space: $O(h)$ for recursion stack where $h$ is tree height. On balanced trees, $h = \log n$ . On skewed trees, $h = n$ .