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Foundation-level problems that each map cleanly to one pattern. Master these first — they are the gateway to every medium and hard question an interviewer will throw at you.
Grouped by curriculum module
Study guide
Overview
Easy problems are where every strong DSA preparation begins. Each one maps cleanly to a single pattern — a hash map, a single pass, a two-pointer sweep — so they are perfect for building the muscle memory you'll lean on under interview pressure. Do not skip them because they look trivial: interviewers open phone screens with "easy" questions and judge you on how cleanly and quickly you reach the optimal solution, not just whether you eventually get there.
We index 141 easy problems, each solved brute-force → optimal in Java and Python with a line-by-line walkthrough and the talking points an interviewer wants to hear. Work through them grouped by module so related ideas reinforce each other.
The goal at this tier is fluency. You should be able to recognise the pattern in seconds, state the time and space complexity without thinking, and write a clean, bug-free solution on the first try.
Study playbook
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