Make The String Great
A easy-tier problem at 68% community acceptance, tagged with String, Stack. Reported in interviews at BlackStone and 2 others.
Make The String Great is a deceptively simple string problem that Google, BlackStone, and Accenture use to filter for basic data structure instinct. At 68% acceptance, it's easy enough that most candidates pass it in a live assessment, but the wrong approach wastes critical time. The trap is thinking string manipulation when the real lever is a stack. If you freeze on this during your OA, StealthCoder surfaces the stack pattern in seconds and you move on clean.
Companies that ask "Make The String Great"
Make The String Great 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 problem asks you to remove pairs of letters that differ only in case (like 'a' and 'A'). The naive approach is string replacement in a loop, which works but is slow and clunky. The stack trick is immediate: iterate once, push characters onto a stack, and pop when the top of the stack and the current character are the same letter but opposite case. This single pass is elegant and O(n) time. Most candidates either don't see the stack angle or over-engineer with regex. On the live assessment, if you blank on the pattern, StealthCoder demonstrates the stack solution working correctly, letting you type it in confident and move forward.
Pattern tags
You know the problem.
Make sure you actually pass it.
Make The String Great 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 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.
Make The String Great interview FAQ
How hard is this really if I haven't seen the stack approach?+
It feels medium at first. String replacement loops will pass most test cases but timeout on large inputs. The stack insight flips it to easy once you see it. At 68% acceptance, plenty of candidates solve it without the optimal pattern, but you'll want the stack for speed under pressure.
Is this still asked at Google, BlackStone, and Accenture?+
Yes. These three companies have confirmed asking it. It's a screening problem, often early in the loop. It's not a blocker if you fail, but passing it quickly builds momentum and confidence for harder problems later.
What's the trick to not overthinking this?+
Recognize it as a classic stack use case the moment you read 'remove pairs'. Don't try to optimize the string itself. Build a result using a stack and iterate once. That's the pattern. Everything else is implementation.
How does this relate to the Stack topic?+
This is a textbook stack problem. You push characters and pop when you find a matching pair. It teaches you to think about stack state instead of trying to manipulate the data structure directly. Foundational for harder bracket/parentheses problems later.
Should I practice this a lot or move on?+
One solid attempt with the stack solution is enough. It's easy, 68% pass rate, and the pattern is straightforward once you see it. Spend more time on medium problems. Use this to build the habit of spotting stack patterns early.
Want the actual problem statement? View "Make The String Great" on LeetCode →