Remove Adjacent Almost-Equal Characters
A medium-tier problem at 52% community acceptance, tagged with String, Dynamic Programming, Greedy. Reported in interviews at Salesforce and 0 others.
Remove Adjacent Almost-Equal Characters is a medium-difficulty problem that appears in Salesforce interviews. With an acceptance rate just above 50%, it's a solid wall for candidates who haven't drilled the greedy pattern. The problem tests whether you can recognize that a string-manipulation problem on the surface is really about making local decisions fast. You need to know when brute-force simulation works and when it doesn't. If this hits your assessment and you blank on whether to use a stack or DP, StealthCoder solves it in seconds, invisible to the proctor.
Companies that ask "Remove Adjacent Almost-Equal Characters"
Remove Adjacent Almost-Equal Characters 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 engineer who got tired of watching his cohort grind for six months and still get filtered at the OA stage.
Get StealthCoderThe trick here is recognizing that you can't always process the string left-to-right in a single pass. When you remove adjacent characters that differ by exactly 1, the characters on either side of the gap suddenly become adjacent. You need to handle cascading removals. Most candidates start with string.replace() in a loop or a naive simulation, which works but hides the insight. The efficient approach uses a stack: you process each character, and if the top of the stack differs by 1, you pop instead of push. This single greedy choice eliminates cascades in one pass. String, Dynamic Programming, and Greedy are all listed as topics, but the Greedy framing is where the real problem lives. StealthCoder becomes your hedge the moment you realize your first approach times out or you're not sure if the stack shortcut is correct.
Pattern tags
You know the problem.
Make sure you actually pass it.
Remove Adjacent Almost-Equal Characters 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 engineer who got tired of watching his cohort grind for six months and still get filtered at the OA stage. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Remove Adjacent Almost-Equal Characters interview FAQ
Is this problem actually asked at real companies?+
Yes, Salesforce has asked it in their assessment. With a 51% acceptance rate, roughly half the candidates who face it get it wrong. It's not a household name like 'Two Sum', but it's real and it shows up.
What's the trap that makes this a medium, not easy?+
The cascading removal. Remove one pair and new pairs become adjacent. A naive loop-and-rebuild works but is slow. The stack approach handles it in one pass, but you have to see the pattern first. That gap between obvious and efficient is where the difficulty lives.
Do I need dynamic programming for this?+
No. DP is listed as a topic but the greedy stack solution is faster and cleaner. DP would work if you tried to memoize subproblems, but it's overkill. The problem setter likely listed it to test whether you pick the right tool.
How do I know if my approach is correct before submitting?+
Test on a case with cascading removals, like a string where removing one pair triggers another removal. If your solution handles that in one pass without re-scanning, it's probably right. If you're looping until no more changes happen, you have the right idea but not the optimal form.
How much time should I spend on this in an assessment?+
If you see the stack pattern immediately, 5-8 minutes. If you start with the loop approach and it works, don't optimize unless you hit a timeout. The accept rate suggests many people get it right the first way. Move on if you're confident.
Want the actual problem statement? View "Remove Adjacent Almost-Equal Characters" on LeetCode →