Utility

Common includes, debugging helpers, and random-number utilities.

Headers

Header	Summary
combinations.hpp	Enumerate all increasing k-subsets of [0,n) in lexicographic order, invoking callback(span-like vector); stop early when it returns false.
coordinate_compression.hpp	Sorted unique coordinates with exact rank and lower/upper-rank queries, plus bulk encoding and decoding.
debug.hpp	Lightweight debug-printing helpers for local competitive-programming builds.
head.hpp	Common C++23 includes and aliases used by the rest of the library.
io.hpp	Fast standard-stream setup and exact signed 128-bit decimal I/O. Disabling C/C++ stream synchronization removes redundant buffering. Decimal parsing accumulates an unsigned magnitude so the minimum signed value is representable; formatting performs the inverse repeated division without ever negating that minimum value in signed arithmetic.
rnd.hpp	Seeded random-number helpers for tests and randomized algorithms.