Medium DSA Interview Questions

Medium is the difficulty that decides most interviews. The overwhelming majority of onsite coding questions at top companies sit here: they combine two or more ideas (a hash map plus a sliding window, a sort plus a two-pointer sweep, a BFS with state) and reward candidates who can decompose a problem into known patterns. If you can reliably solve mediums, you can pass most loops.

We index 226 medium problems, each worked brute-force → optimal in Java and Python with line-by-line explanations and the "what to say in the interview" framing. They're grouped by module so you can drill one pattern at a time rather than jumping randomly.

The skill to develop here is composition — seeing that a problem is "sliding window plus a frequency map" and reaching for both. That comes from deliberate, pattern-by-pattern practice, not random grinding.