Problem sheets
Practice, by topic.
Hand-picked CodeForces problems grouped into focused sheets. Open any problem on CodeForces, or jump straight into CP Ally IDE.
Introduction for Beginners
A first ladder into competitive programming — 100 of the most-solved CodeForces problems, ordered by rating. 40 rated 800, 40 rated 900, and 20 rated 1000.
Basics of Number Theory
Build a foundation in number theory — 100 CodeForces problems tagged number theory, laddered from 800 up to 1400 as the ideas get sharper.
Basics of Bit Manipulation
Get comfortable thinking in bits — 100 CodeForces problems tagged bitmasks, laddered from 800 up to 1400 as the tricks compound.
Basics of Dynamic Programming
Learn to break problems into subproblems — 100 CodeForces problems tagged dp, laddered from 800 up to 1400 as the states get richer.
Basics of Strings
Sharpen your string-handling instincts — 100 CodeForces problems tagged strings, laddered from 800 up to 1400 across every rating tier.
Basics of Hashing
Get a feel for hashing techniques — 40 CodeForces problems tagged hashing, laddered from 800 up to 1700 (the range was widened since few hashing problems sit at the lowest ratings).
Basics of Sorting
Master sorting and the ideas built on it — 100 CodeForces problems tagged sortings, laddered from 800 up to 1400 across every rating tier.
Basics of Mathematics
Strengthen the math instincts behind problem-solving — 100 CodeForces problems tagged math, laddered from 800 up to 1400 across every rating tier.