#Hockey-Stick

2 posts

Combinatorics #1.1 April 24, 2026 9 min read

Permutations and Combinations

Hockey Stick identity, addition/multiplication principles, binomial identities, example problems: bitonic sequences, multiset permutations, multi-layer coloring DP, CCPC Subpermutation.

#math #combinatorics #permutation #combination #hockey-stick

Combinatorics D1 April 24, 2026 13 min read

Diophantine Equations

Stars and bars, bounded Diophantine equations via inclusion-exclusion, prefix-sum DP, D&C NTT, equal-cap formula, and a full worked example on CF 2127F.

#math #combinatorics #diophantine #stars-and-bars #inclusion-exclusion