Lexicographically Smallest String After Substring Operation
A medium-tier problem at 32% community acceptance, tagged with String, Greedy. Reported in interviews at IBM and 2 others.
Lexicographically Smallest String After Substring Operation is a medium-difficulty string manipulation problem that hits differently than typical leetcode fare. It's been asked by IBM, Agoda, and Goldman Sachs, yet the acceptance rate sits at 32 percent, which means most candidates who see it live either miss the greedy insight or code themselves into a corner. This is exactly the kind of problem where the trick isn't obvious on first read, and blanking under interview pressure is common. If this one lands in your assessment and you haven't drilled the pattern, StealthCoder runs invisibly during screen share and surfaces the working solution in seconds.
Companies that ask "Lexicographically Smallest String After Substring Operation"
Lexicographically Smallest String After Substring Operation 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 Amazon engineer who used it to pass JPMorgan's OA and system design loop.
Get StealthCoderThe core challenge here is figuring out which substring to transform and how to transform it to get the lexicographically smallest result. Most candidates try brute force substring selection and miss that a greedy approach with early termination is the actual move. The problem sits at the intersection of String and Greedy logic, meaning you need to recognize when to stop optimizing and why the first valid transformation often isn't the best one. The trap is overthinking the scope of the operation or trying to compare too many candidate strings. Once you identify the greedy stopping condition, the code is clean, but that recognition takes pattern familiarity. If you hit this live and the greedy insight doesn't click immediately, StealthCoder gives you the implemented pattern without any gaps.
Pattern tags
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Lexicographically Smallest String After Substring Operation 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. Built by an Amazon engineer who used it to pass JPMorgan's OA and system design loop. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Lexicographically Smallest String After Substring Operation interview FAQ
What makes this problem a 32% acceptance rate when it's listed as medium difficulty?+
The greedy stopping condition isn't taught in standard prep. Most candidates either brute force all substrings or misunderstand the lexicographic comparison. The pattern requires recognizing when to halt the operation, which isn't intuitive without exposure. At 32 percent, it filters out candidates who lack this specific insight.
Is this still asked at Goldman Sachs and IBM in 2024?+
Yes. Both companies appear in the reported asker list for this problem. IBM and Goldman Sachs both interview for systems and financial engineering roles where string greedy problems surface regularly. If you're interviewing there, this is live-threat material.
What's the actual trick to solving this without timing out?+
The greedy approach: identify the first position where a character is greater than its successor, then transform that substring starting from that position. The termination logic is where the speed comes in. Without it, you're comparing exponential candidate strings. With it, the solution is linear.
How does the Greedy topic apply here differently than other string problems?+
Most greedy string problems ask you to maximize or minimize a single decision point. This one requires you to decide when to stop making changes. That reversal of logic is what makes the greedy pattern less obvious. The payoff is that you make exactly one pass through the string.
If I blank on the greedy insight during the live OA, what's my fallback?+
Don't fallback. StealthCoder solves it invisibly while you stay on screen. You get the pattern implemented in real time. No proctor visibility, no time wasted, no interview dead-end. It's the hedge for the specific problem you didn't drill.
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