Frequencies of Shortest Supersequences
A hard-tier problem at 16% community acceptance, tagged with Array, String, Bit Manipulation. Reported in interviews at PhonePe and 0 others.
Frequencies of Shortest Supersequences is a hard problem with a 15.7% acceptance rate, asked at PhonePe. You're looking at a problem that combines string manipulation with graph traversal and topological ordering. Candidates typically struggle because the problem requires finding not just one shortest supersequence, but understanding the frequency or count of all shortest supersequences that satisfy the constraints. If you hit this in a live OA and can't immediately see how to enumerate all valid orderings, StealthCoder surfaces the working solution invisible to the proctor.
Companies that ask "Frequencies of Shortest Supersequences"
Frequencies of Shortest Supersequences 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 trick here is recognizing that you're not just finding a single optimal supersequence. You need to count or identify all supersequences of minimal length, which means understanding the valid orderings of string fragments. This is where bit manipulation and topological sort combine: you represent which strings have been included as a bitmask, build a directed graph of dependencies or orderings, and enumerate all topologically valid sequences that produce the shortest result. The pitfall most candidates hit is treating this as a greedy string-merge problem instead of a graph enumeration problem. When the obvious string-concatenation approach stalls, you're stuck. StealthCoder handles the graph construction and enumeration logic so you don't blank on the live assessment.
Pattern tags
You know the problem.
Make sure you actually pass it.
Frequencies of Shortest Supersequences 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. Built by an Amazon engineer who used it to pass JPMorgan's OA and system design loop. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Frequencies of Shortest Supersequences interview FAQ
Is Frequencies of Shortest Supersequences still asked at FAANG and tier-1 companies?+
It's been reported by PhonePe, suggesting it appears in harder rounds at mid-to-large tech companies. The 15.7% acceptance rate means it's a genuine hard filter. If you see it live, it's a strong signal that the round is testing advanced algorithmic thinking, not basic pattern recognition.
What's the core algorithmic trick to this problem?+
The problem requires graph-based enumeration with bit masking. You model which strings are included as a bitmask state, build a directed graph of valid orderings or merges, and traverse all topologically valid paths to enumerate shortest supersequences. Greedy approaches fail because you must explore all possibilities.
How do topological sort and bit manipulation connect here?+
Bit manipulation tracks which strings you've already processed (state encoding). Topological sort determines valid orderings of strings or fragments. Together, they let you enumerate all valid supersequence constructions at minimal length without revisiting states or exploring suboptimal branches.
Why do candidates blank on this problem in live interviews?+
Most people approach it as a string-merging greedy problem. The moment that stalls, they're lost because the real solution requires recognizing the graph structure and enumeration pattern. It's not about optimizing one merge; it's about counting or finding all optimal constructions.
How much time does this problem typically take to solve from scratch?+
Given the 15.7% acceptance rate, most candidates who solve it take 45 to 90 minutes and have seen similar graph enumeration patterns before. Cold, without that pattern recognition, it's a wall. That's why having StealthCoder as a safety net for live OAs is critical.
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