Knight Dialer: Count Dialable Digit Sequences

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Q: What difficulty level is this coding question?

This is a medium difficulty Coding & Algorithms question, commonly asked during Technical Screen rounds at Whatnot.

Q: What role is this question designed for?

This question is commonly asked for Software Engineer candidates at Whatnot during technical interviews.

Question

Knight Dialer: Count Dialable Digit Sequences

PracHub · Accepted Answer

This question evaluates a candidate's ability to model constrained state transitions with dynamic programming, using a knight's legal moves on a phone keypad as the domain. It tests recognition that counting sequences under fixed transition rules reduces to tracking per-digit counts over discrete steps, a common way to probe DP-over-graph thinking in coding interviews. The problem sits at a practical application level, requiring an efficient algorithm rather than brute-force path enumeration.

Quick Overview

Knight Dialer: Count Dialable Digit Sequences