Number of Ways to Divide a Long Corridor
A hard-tier problem at 49% community acceptance, tagged with Math, String, Dynamic Programming. Reported in interviews at Zomato and 0 others.
You're staring at a corridor divided into sections, and you need to count the ways to split it. This problem hits hard because it's not a standard DP grid or string problem, even though those are in the topic list. Zomato has asked it. The acceptance rate is 48%, which means half the candidates who submit get it wrong. Most miss that the trick isn't about recursion or classic DP states, it's about recognizing a mathematical pattern in how seats and walls interact. If this problem shows up in your live OA and you blank on the insight, StealthCoder solves it in seconds, invisible to the proctor.
Companies that ask "Number of Ways to Divide a Long Corridor"
Number of Ways to Divide a Long Corridor 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 corridor has seats and walls. You need to place dividers such that each section has exactly two seats. The catch: this isn't a simulation problem. Once you see that valid dividers only go between specific pairs of seats, the problem flips into pure math. You're counting positions where a divider can go, factoring in consecutive valid positions. Most candidates start building a DP table or try to simulate placement, which works but misses the elegance. The real solution counts the gaps between valid seat pairs, then multiplies those counts together. It's combinatorial, not iterative. If you hit the wall during the assessment, StealthCoder removes the friction and gives you the working approach so you can move on.
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Number of Ways to Divide a Long Corridor 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 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.
Number of Ways to Divide a Long Corridor interview FAQ
Is this really a DP problem or a math problem?+
It's listed under Dynamic Programming, but that's a red herring for most candidates. The actual solution is mathematical: counting gaps between valid divider positions and multiplying them. DP thinking can lead you down a slower path. The insight is recognizing the structure first.
How hard is this compared to other hard problems?+
The 48% acceptance rate shows it's genuinely hard, but not because of code complexity. It's hard because the trick is non-obvious. Once you see the pattern, implementation is short. Many hard problems are hard to code; this one is hard to conceptualize.
Why would a company like Zomato ask this?+
It tests whether you can recognize patterns and translate them into math, not just whether you can code a loop or build a tree. It's a signal that the candidate can think beyond brute force and see the problem's true structure.
What's the most common way candidates fail?+
They try to simulate or use a standard DP state like 'ways to reach position i with k seats in last section.' Simulation works for small inputs but times out. Missing the gap-multiplication insight leaves you building when you should be counting.
Is String really a topic here, or is that just indexing?+
The input is a string representing the corridor, so yes, String is a topic. But the problem isn't about string matching or manipulation. It's parsing the corridor to find seats, then using math on the distances between them. Don't expect classic string techniques.
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