Remove Colored Pieces if Both Neighbors are the Same Color
A medium-tier problem at 63% community acceptance, tagged with Math, String, Greedy. Reported in interviews at Yelp and 4 others.
You're staring at a colored string where pieces vanish if both neighbors match. Yelp, Unity, and J.P. Morgan ask this one. It looks like a simulation problem at first, but the greedy or game-theory angle trips most candidates. The string shrinks and reshapes as you remove pieces, so the naive approach of iterating and deleting doesn't catch the cascading effects. Your interview has maybe 45 minutes left when this lands. StealthCoder solves it invisibly the moment you hit a wall, surfacing a working solution before the proctor notices.
Companies that ask "Remove Colored Pieces if Both Neighbors are the Same Color"
Remove Colored Pieces if Both Neighbors are the Same Color 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 at a top-10 tech company who can solve these problems cold but didn't want to trust himself in a 90-minute screen share.
Get StealthCoderThe core insight is recognizing that this isn't a simple left-to-right scan. When you remove a piece, previously non-adjacent neighbors become adjacent, and they might now both match the remaining piece between them. A stack-based greedy approach works well: push characters onto a stack, and before each push, check if the top two elements and the incoming character form a removable pattern. This avoids the trap of re-scanning the whole string after each deletion. Math and string manipulation combine here, and the game-theory framing (optimal removal strategy) can matter in variant forms. Most candidates waste time on index tracking or rebuild loops. StealthCoder identifies the pattern instantly during your live assessment, letting you code confidently instead of backtracking.
Pattern tags
You know the problem.
Make sure you actually pass it.
Remove Colored Pieces if Both Neighbors are the Same Color 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 at a top-10 tech company who can solve these problems cold but didn't want to trust himself in a 90-minute screen share. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Remove Colored Pieces if Both Neighbors are the Same Color interview FAQ
Is this really a medium difficulty problem?+
Yes. Acceptance rate hovers near 63%, which confirms medium classification. It's not a trick problem, but the cascading-removal logic isn't obvious on first read. Candidates who've drilled stack problems solve it faster.
Do I need game theory knowledge to pass?+
For the standard version, no. Greedy and string manipulation are sufficient. Game theory appears in the topic list because some variants involve optimal play or strategy, but the core problem is solvable with greedy logic alone.
Why does simulation fail here?+
Simulation (repeatedly scan and remove until no more matches) works but is inefficient and error-prone in interviews. You're rebuilding the string or managing indices constantly. A stack handles cascading removals in a single pass, which is what interviewers expect.
How does this relate to other string problems?+
It combines ideas from parenthesis matching (stack-based pattern detection) and greedy string manipulation. If you're comfortable with stack-based string problems, this is a natural next step. Yelp and Unity both ask variants.
What's the most common mistake?+
Forgetting that removal triggers new adjacencies. Candidates iterate character by character and delete without considering that the string changes shape. Stack-based solutions avoid this entirely by handling cascading matches naturally.
Want the actual problem statement? View "Remove Colored Pieces if Both Neighbors are the Same Color" on LeetCode →