Combinatorics problem on multisets.

Little number theory puzzle.

Crossing a bridge while satisfying constraints.

Dutch National Flag Problem.

FFT uses.

Reasoning with loop invariants.

Cool proof of the Schröder-Bernstein Theorem.

Program calculus problem.

Line of airline passengers boarding a plane.

Induction and integer inequalities.

Inclusion-exclusion in combinatorics.

Network flows and vertex covers.

Hamming codes solve an impossible looking puzzle.

Little nugget.

Coin weighings problems.

Variants of the Bernoulli inequality.

Completeness of the Reals.

Infinite countable sets.

Combinatorics and probability.

Loop invariants.