75 data structures & algorithms problems, grouped by the pattern they teach and ordered from foundational to advanced: arrays and hashing through two pointers, sliding window, stacks, binary search, linked lists, trees, tries, heaps, backtracking, graphs, dynamic programming, and greedy. Free to read, no signup required.
How to use this: work down the list in order. Each problem lists its difficulty and a one-line hint toward the technique, not the full solution. Attempt a problem before reading its hint, and revisit a category once the pattern clicks rather than grinding every problem in one sitting.
Frequently asked questions
For most mid-level interviews, yes, if you genuinely understand the pattern behind each problem rather than memorizing the solution. These 75 cover every pattern that shows up repeatedly across real interviews; a much longer list mostly adds more of the same pattern rather than new ones.
Top to bottom. The categories are ordered from foundational (arrays, two pointers) to more advanced (graphs, dynamic programming), and later categories lean on comfort with earlier ones, especially recursion for trees, backtracking, and DP.
Try the problem cold for at least fifteen to twenty minutes first. The hint here is a nudge toward the pattern, not a full solution, and struggling productively before checking it is what actually builds the skill.
No. If a pattern clicks after three or four problems, move to the next category and come back later. Revisiting a category after a break, once you have more pattern recognition, is often more useful than grinding it in one sitting.
Read an editorial or explanation, understand the approach fully, then close it and re-solve it from scratch a day or two later without looking. Copying a solution without re-deriving it later rarely sticks.
This is a free, general-purpose practice list. Interview Ready builds a personalized 30-day plan around your resume and a specific target role, sequencing DSA practice with system design and behavioural prep in the right order for that role.
Want these sequenced into a full interview plan?
This list is the practice set. Interview Ready turns it into a personalized 30-day plan built around your resume and a specific target role: DSA in the right order, plus system design and behavioural prep, with a guided Build-a-Project track alongside it. Start free.
