Ternary Expression Parser
A medium-tier problem at 62% community acceptance, tagged with String, Stack, Recursion. Reported in interviews at Snap and 0 others.
Ternary Expression Parser is a medium-difficulty problem that tests your ability to parse conditional expressions without a built-in parser. Snap has asked this one. The trap is treating it like a simple string walk. Most candidates either recurse incorrectly on the nested ternary or use a stack inefficiently, burning time on edge cases. The acceptance rate sits at 62 percent, which means a decent chunk of people hit submit and fail. If this lands in your live assessment and you blank on the recursion order, StealthCoder solves it in seconds, invisible to the proctor.
Companies that ask "Ternary Expression Parser"
Ternary Expression Parser 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. Made by an Amazon engineer who watched the leaked-problem repo become an industry secret. He decided you should have it too.
Get StealthCoderThe trick is understanding that ternary expressions nest right-to-left. A naive left-to-right walk fails immediately on nested ternaries. You have to either recurse with a position pointer that skips past sub-expressions, or use a stack to track pending conditions and results. The String and Stack topics are both viable, but recursion is cleaner if you track your index correctly. Common failure: processing the false branch before the true branch, or losing track of where you are in the string during recursion. The problem forces you to respect operator precedence at parse time, not just evaluate time. If you've drilled recursive descent parsing before, this clicks fast. If not, you'll waste 20 minutes on off-by-one bugs. StealthCoder is the hedge for the one parsing pattern you didn't drill before the OA.
Pattern tags
You know the problem.
Make sure you actually pass it.
Ternary Expression Parser recycles across companies for a reason. It's medium-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. Made by an Amazon engineer who watched the leaked-problem repo become an industry secret. He decided you should have it too. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Ternary Expression Parser interview FAQ
Is this still actively asked at big tech?+
Snap has reported it. It's not a FAANG staple like two-sum, but parsing problems do surface in live assessments. The acceptance rate of 62 percent tells you it's moderate-hard in practice. Not everyone nails it first try.
What's the actual trick I'm missing?+
Ternary expressions are right-associative. The expression a?b:c?d:e parses as a?(b):(c?d:e), not (a?b:c)?(d):(e). Recursion or explicit stack discipline forces you to handle the right branch fully before returning. Left-to-right greedy parsing breaks.
Stack or recursion, which is faster to code?+
Recursion is faster to code if you track the position index correctly. Stack is more explicit but requires careful bracket matching logic. For live OA speed, recursion wins. Just don't lose your index pointer in nested calls.
How does this relate to the other String and Stack topics?+
String parsing is the problem surface. Stack and Recursion are two different control-flow patterns to solve it. Stack mimics a call stack; recursion uses the actual call stack. Either works, but they expose different edge cases.
What's the time complexity, and does it matter?+
Single pass through the string is O(n). Most candidates hit that. Space complexity (call stack or explicit stack) is O(depth of nesting). Interview-style, the complexity is rarely the blocker. Correctness and not timing out on nested ternaries is.
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