Binary Tree Maximum Path Sum
A hard-tier problem at 41% community acceptance, tagged with Dynamic Programming, Tree, Depth-First Search. Reported in interviews at Citadel and 26 others.
Binary Tree Maximum Path Sum is a hard problem that 27 companies ask, including Citadel, DoorDash, Salesforce, and Baidu. Only 41% of candidates solve it on first attempt. The trick isn't dynamic programming or tree traversal alone, it's realizing that the maximum path doesn't have to include the root, and that you must track two things simultaneously: the best path through each node, and the best path seen globally. This distinction catches most people. If you hit this live and freeze on the recursion logic, StealthCoder surfaces a working solution in seconds, invisible to the proctor.
Companies that ask "Binary Tree Maximum Path Sum"
Binary Tree Maximum Path Sum is the kind of problem that decides whether you pass. StealthCoder reads the problem on screen and surfaces a working solution in under 2 seconds. Invisible to screen share. The proctor sees nothing. Built by an engineer at a top-10 tech company who can solve these problems cold but didn't want to trust himself in a 90-minute screen share.
Get StealthCoderThe naive approach fails because you can't just sum all positive values, paths must be contiguous and connected. The real pattern: at each node, compute the maximum path that ends at that node (for passing upward), while tracking the global maximum (which might bend at this node and go both left and right). Most candidates build the tree traversal correctly but forget to update the global max with the 'bent' path that uses both subtrees. The recursion must return only the single best arm (left or right plus current), never both. That's where the logic breaks. When you're writing this under pressure in the live assessment and can't quite get the state right, StealthCoder runs invisibly and gives you the working pattern so you can type it out.
Pattern tags
You know the problem.
Make sure you actually pass it.
Binary Tree Maximum Path Sum recycles across companies for a reason. It's hard-tier, and most candidates blank under the timer. StealthCoder is the hedge: an AI overlay invisible during screen share. It reads the problem and surfaces a working solution in under 2 seconds. Built by an engineer at a top-10 tech company who can solve these problems cold but didn't want to trust himself in a 90-minute screen share. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Binary Tree Maximum Path Sum interview FAQ
Is this still asked at FAANG-tier companies?+
Yes. Citadel, DoorDash, Salesforce, and Baidu all report it. It's a go-to hard problem for companies that care about tree DP and recursive thinking. The 41% acceptance rate shows it separates strong candidates from the rest.
What's the actual trick to Binary Tree Maximum Path Sum?+
Track two things at every node: the max path ending at this node (to return to parent) and the max path seen anywhere (which can bend through the node). Most failures forget the global max update when combining left and right subtrees. Return only the best single-arm path upward, never both subtrees together.
How does this relate to other tree DP problems?+
It combines Depth-First Search tree traversal with Dynamic Programming state. You can't solve it with just greedy logic or simple DFS. Like other hard tree problems, it requires you to compute and return subproblem answers (max path from this node) while maintaining global state in parallel.
What languages should I practice this in?+
Python is fastest for tree recursion. Java and C++ work but require more boilerplate. You don't need to optimize for speed here, clarity on the recursion logic matters more. One clean recursive function with careful state updates beats a fast muddy solution.
Why is the acceptance rate so low?+
The recursion state is non-obvious. Most candidates build DFS correctly but fail to separate 'max path ending here' from 'best path anywhere.' The off-by-one logic in combining subtrees and updating global max trips up 59% of first-timers, even experienced ones.
Want the actual problem statement? View "Binary Tree Maximum Path Sum" on LeetCode →