Invert Binary Tree
A easy-tier problem at 79% community acceptance, tagged with Tree, Depth-First Search, Breadth-First Search. Reported in interviews at Ozon and 2 others.
Invert Binary Tree is an easy problem that shows up in OAs at Amazon, Oracle, and Ozon. With a 79% acceptance rate, it feels like a gimme until you sit down live and realize you're second-guessing the recursion or mixing up left/right assignments. This is the kind of problem where a blank moment costs you confidence on the next five problems. StealthCoder runs invisibly during your assessment and surfaces a working solution in seconds if you hit the wall, so you stay in flow.
Companies that ask "Invert Binary Tree"
Invert Binary Tree 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 a senior engineer who knows the OA is theater. This is the script.
Get StealthCoderThe trick is simple but easy to fumble under pressure: swap left and right subtrees at every node, then recurse. Most candidates think in terms of a single recursive call that touches both children. The real pattern is that you must invert the entire left subtree, invert the entire right subtree, then swap them. DFS is the natural fit, though BFS works too. The gotcha is mixing up your assignment order or forgetting that you're modifying the tree structure as you go. If you haven't seen this exact pattern drilled, you waste time rebuilding the logic. StealthCoder eliminates that risk by handling the live version while you stay calm.
Pattern tags
You know the problem.
Make sure you actually pass it.
Invert Binary Tree recycles across companies for a reason. It's easy-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 a senior engineer who knows the OA is theater. This is the script. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Invert Binary Tree interview FAQ
Is Invert Binary Tree still asked at big tech companies?+
Yes. Amazon, Oracle, and Ozon all report it. The 79% acceptance rate doesn't mean it's rare, it means most who attempt it pass. Companies use it as a warm-up or screening filter because it's fast to code and reveals whether you can think recursively.
What's the actual trick I need to remember?+
Swap left and right children at each node, then recurse on both subtrees. Don't try to invert 'in place' and recurse at the same time. Separate the concerns: invert left, invert right, swap them. That clarity prevents off-by-one recursion bugs.
Do I need both DFS and BFS solutions ready?+
DFS is the standard approach and maps naturally to the recursive structure. BFS (queue-based level order) works but is overkill. Master DFS recursion first. If they ask for BFS, the logic is the same, just use a queue instead of the call stack.
How does Invert Binary Tree relate to other tree problems I should know?+
It's foundational for understanding tree traversal and mutation. Once you own this, problems like Same Tree, Symmetric Tree, and Merge Two Binary Trees click because they all use similar recursive patterns on paired subtrees.
What if I blank on the recursion during the live assessment?+
StealthCoder is your safety net. It reads the problem off your screen and provides a working solution in real time, invisible to the proctor. You copy the pattern, understand it, and move forward without panic tanking your next problems.
Want the actual problem statement? View "Invert Binary Tree" on LeetCode →