Groups of Strings
A hard-tier problem at 27% community acceptance, tagged with String, Bit Manipulation, Union Find. Reported in interviews at Lowe's and 0 others.
Groups of Strings is a hard problem that's been asked at Lowe's and sits at a 27% acceptance rate, which means most candidates don't nail it on first try. You're looking at a string-grouping problem that hinges on recognizing which strings belong together based on a non-obvious pattern. The trick isn't complicated once you see it, but walking in cold means you'll burn time trying string comparisons that don't work. If this problem hits your live OA and you blank on the grouping condition, StealthCoder runs invisibly during the assessment and surfaces a working solution in seconds.
Companies that ask "Groups of Strings"
Groups of Strings 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 for the engineer who has done the work but might still blank with a webcam pointed at him.
Get StealthCoderThe core challenge here is figuring out which strings should be grouped together, and the answer lives in bit manipulation and union find. The grouping condition typically involves comparing the character sets of strings in a clever way, not just looking at values or frequencies. Most candidates' first instinct is to hash and compare directly, but the actual pattern requires you to represent each string's unique characters as a bitmask, then determine when two strings can belong to the same group. This is where union find clicks in. You build a graph of strings where edges represent the grouping condition, then use union find to collapse connected components. The string and bit manipulation topics aren't separate concerns here, they're intertwined. If you haven't drilled problems that combine these three topics before, StealthCoder is the hedge for the live assessment when the pattern doesn't surface in the first five minutes.
Pattern tags
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Make sure you actually pass it.
Groups of Strings recycles across companies for a reason. It's hard-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 for the engineer who has done the work but might still blank with a webcam pointed at him. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Groups of Strings interview FAQ
Is Groups of Strings still asked at FAANG or major tech companies?+
The input data shows Lowe's as the reported company asking it. Hard problems with 27% acceptance rates typically stay in rotation because they're good signals for senior roles and system-design-capable engineers. It's a reasonable preparation target if you're applying to mid-to-large companies outside pure FAANG.
What's the trick to solving Groups of Strings?+
The grouping condition hinges on comparing the character composition of strings using bit manipulation. Represent each string as a bitmask of its unique characters, then apply union find to group strings that satisfy the condition. The pattern isn't string equality or substring matching. It's about which sets of characters can coexist in the same group.
How do bit manipulation and union find actually work together here?+
Bit manipulation lets you encode which characters appear in a string as a single integer. Union find then merges strings whose bitmasks satisfy the grouping rule into connected components. Together they avoid nested loops over character comparisons and keep the solution efficient enough for the constraints.
Why is the acceptance rate so low for this problem?+
At 27%, most candidates either miss the bit manipulation angle entirely or struggle to apply union find correctly after identifying the pattern. The problem requires combining three separate topic areas in a non-obvious way. Without seeing the pattern, the brute-force approaches time out or produce wrong groups.
What should I prepare if I see this problem in a real OA?+
Review union find implementations and practice problems that use bitmasks to represent sets. Make sure you can quickly sketch a solution that builds edges between strings based on a custom comparison rule, then groups them. If the grouping condition doesn't click in the first two minutes of reading the problem, flag it and move on.
Want the actual problem statement? View "Groups of Strings" on LeetCode →