Design a Text Editor
A hard-tier problem at 47% community acceptance, tagged with Linked List, String, Stack. Reported in interviews at Dropbox and 7 others.
Design a Text Editor is the kind of problem that separates people who understand data structures from people who just memorize solutions. You're building a real editor with cursor movement, insert, delete, and undo/redo. It's asked at Dropbox, Block, Salesforce, Jane Street, Snap, Shopify, Rubrik, and Oracle. The acceptance rate sits at 47%, which means half the room gets stuck on state management or crashes on edge cases. If you hit this live and blank on the structure, StealthCoder surfaces a working implementation in seconds, invisible to the proctor.
Companies that ask "Design a Text Editor"
Design a Text Editor 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 because the OA filter rejects engineers who'd pass the on-site. That's a broken filter. This is the workaround.
Get StealthCoderThe trap is thinking you need a simple string and index. That falls apart on undo/redo or when you realize you're doing O(n) deletes in the middle of text. The real pattern: a doubly-linked list of characters with a cursor pointer. Insert and delete become node operations (O(1) after finding the cursor). Undo/redo need a stack of operations or snapshots. Common failure: cursor tracking after operations, forgetting to handle boundaries, or inefficient snapshot copying. The design problem isn't really about the data structure alone. It's about cleanly separating cursor state, text state, and history. When you're coding live and realize your string-based approach is tanking performance, StealthCoder gives you the linked-list pivot without losing composure.
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Design a Text Editor 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 because the OA filter rejects engineers who'd pass the on-site. That's a broken filter. This is the workaround. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Design a Text Editor interview FAQ
Is this really a 47% problem or is the acceptance rate deflated by terrible implementations?+
It's deflated. Most failures aren't conceptual. They're implementation bugs: off-by-one cursor errors, forgetting to update the cursor after undo, or not handling edge cases like deleting at boundaries. The idea (linked list plus operation stack) is sound once you see it.
Do I actually need undo/redo, or is that optional in the real interview?+
Undo/redo is part of the full spec. Some interviewers ask for a basic version first (insert, delete, cursor movement), then add undo as a follow-up. Assume you need both unless told otherwise. That's where the hard part lives.
Why is Doubly-Linked List listed as a topic if a singly-linked list could work?+
Singly works technically, but moving the cursor left is O(n) every time. Doubly-linked is O(1) in both directions and reflects real editor design. Interview's testing whether you know the difference.
How do I avoid the cursor-tracking bugs that sink most attempts?+
Write a helper function that verifies cursor position invariants after every operation. Test delete at boundaries (start, end, one character). Test undo/redo sequences that cross insert-delete pairs. These edge cases are where implementations fail.
Is this problem still actively asked or is it old news at these companies?+
Eight top companies have reported it, and it's a design hire favorite. It's not trendy, it's structural. Expect it to stay in rotation because it separates linked-list practitioners from people who memorized LeetCode Medium problems.
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