This code collection is maintained mainly for competitive programming, and partly for just understanding algorithms.

The greater part of this library is distributed as public domain, or licensed under either CC0 or the MIT license, whichever gives you the most rights in your legislation. Some code, however, has its specific license (usually because it is a dead copy of other library). For the details, please see the header of each file.

Although I put this code collection in a ASDF module, this project is primarily made for competitive programming and the whole structure will be quite different from a common ASDF library. I don't recommend that you directly load this module for your software.

On portability: I try to write portable code as long as the code structure doesn't get too complicated. However, I occasionally use extensions and behaviours of SBCL x86-64, mainly for performance reasons. Below is a SBCL-specific feature that I always depend on:

• declaration as assertion

Below are the features that I sometimes use:

• bivalent stream
• extensible sequence
• sb-ext:array-storage-vector and sb-kernel:%vector-raw-bits
• sb-c:define-source-transform

Every data structure and algorithm uses a 0-based index and a half-open interval unless otherwise noted.

• SBCL 2.1.6 (x64, linux) — yukicoder's version
• SBCL 2.0.3 (x64, linux) — AtCoder's version
• SBCL 1.3.13 (x64, linux) — CodeChef's version
• SBCL 1.3.1 (x64, linux) — HackerEarth's version

• queue.lisp queue with singly-linked list
• deque.lisp double-ended queue with ring buffer
• double-stack-deque.lisp double-ended queue with two stacks
• binary-heap binary heap for static or dynamic order function
• pairing-heap.lisp meldable heap (pairing heap)
• radix-heap.lisp radix heap
• segment-tree.lisp segment tree over an arbitrary monoid
• simple-dual-segment-tree.lisp dual segment tree for a commutative operator
• persistent-segment-tree.lisp persistent segment tree
• persistent-starry-sky-tree.lisp persistent starry sky tree
• binary-indexed-tree.lisp binary indexed tree (aka Fenwick tree) over an arbitrary commutative monoid
• biset.lisp binary indexed tree for binary data
• 2d-bit.lisp 2D binary indexed tree
• disjoint-set.lisp disjoint set by Union-Find algorithm
• undoable-disjoint-set.lisp undoable disjoint set
• persistent-disjoint-set.lisp partially persistent disjoint set
• offline-dynamic-connectivity.lisp offline dynamic connectivity
• ref-able-treap.lisp ordered set with treap; analogue of std::set or java.util.TreeSet
• explicit-treap.lisp ordered map with treap; analogue of std::map or java.util.TreeMap
• implicit-treap.lisp treap with implicit key
• multiset.lisp multiset
• interval-set.lisp ordered set of half-open intervals
• disjoint-sparse-table.lisp disjoint sparse table on arbitrary semigroup
• range-tree.lisp 2D range tree over an arbitrary commutative monoid
• range-tree-fc.lisp 2D range tree with fractional cascading
• convex-hull-trick.lisp convex hull trick
• succinct-bit-vector.lisp three-layer succinct bit vector
• compact-bit-vector.lisp two-layer compact bit vector
• wavelet-matrix.lisp wavelet matrix
• persistent-vector.lisp persistent vector
• dice.lisp six-sided dice
• swag.lisp sliding window aggregation
• sliding-window.lisp sliding window extremum

• cumulative-sum.lisp n-dimensional cumulative sum
• bisect.lisp analogue of std::lower_bound and std::upper_bound
• trisect.lisp extremum of strictly unimodal function
• monotone-minima.lisp divide-and-conquer algorithm for monotone matrix
• quicksort.lisp quicksort
• merge-sort.lisp merge sort
• inplace-merge-sort.lisp in-place merge sort
• binsort.lisp bin sort; counting sort
• map-permutations.lisp permutation and combination
• next-permutation.lisp next permutation w.r.t. lexicographical order
• inversion-sequence.lisp inversion sequence of permutation
• mo.lisp Mo's algorithm
• inverse-table.lisp inverse lookup table of vector
• adjacent-duplicates.lisp deletion of adjacent duplicates
• run-length.lisp run-length encoding
• inversion-number.lisp counting inversions of vector by merge sort
• lis.lisp longest increasing subsequence
• mex.lisp minimum excludant on non-negative integers
• quickselect.lisp expected O(n) algorithm for k-th order statistic of sequence
• symmetric-group.lisp decomposition to cyclic permutations and some operations on a symmetric group
• fkm.lisp Fredricksen, Kessler, and Maiorana algorithm
• manhattan-fnn.lisp farthest neighbor points in d-dimensional L1 space
• round-robin.lisp scheduling algorithm for a round robin tournament (circle method)
• hackenbush.lisp game value of Hackenbush
• date.lisp some utilities about date

• mod-power.lisp modular exponentiation
• ext-gcd.lisp extended euclidean algorithm
• mod-inverse.lisp modular inverse
• mod-log.lisp modular logarithm
• bsgs.lisp baby-step giant-step algorithm for discrete logarithm problem on (semi)group
• bezout.lisp Bezout equation
• mod-linear-algebra.lisp modular linear algebra
• power.lisp exponentiation over an arbitrary monoid
• binom-mod-prime.lisp binomial coefficient modulo prime; linear-time construction of tables of inverses, factorials, and inverse of factorials
• binom-mod-small.lisp binomial coefficient modulo small number
• partition-number.lisp partition number
• bounded-partition-number.lisp partition number with upper-bound
• perfect-kth-powers.lisp sequence of perfect powers
• eulerian-polynomial.lisp Eulerian polynomial
• mod-operations.lisp modular arithmetic
• lagrange-interpolation.lisp Lagrange interpolation
• eratosthenes.lisp enumeration of primes; prime factorization
• linear-sieve.lisp linear sieve; fast prime factorization
• divisor.lisp enumeration of divisors of a given number
• divisor-table.lisp enumeration of divisors of first n natural numbers
• primality.lisp primality test (deterministic Miller-Rabin)
• integer-root integer nth root
• gemm.lisp matrix multiplication over semiring
• freiwald.lisp Freiwalds' algorithm
• f2.lisp linear algebra on GF(2)
• walsh-hadamard.lisp fast Walsh-Hadamard transform
• zeta-transform.lisp fast zeta/Möbius transform
• zeta-integer.lisp fast zeta/Möbius transform w.r.t. divisors or multiples of integer
• farey.lisp iteration on Farey sequence
• farey-next.lisp next/previous element on Farey sequence
• hermite-normal-form.lisp Hermite normal form
• lll.lisp LLL algorithm for basis reduction

• fft.lisp complex FFT (radix-2)
• fft-real.lisp real FFT (radix-2)
• fft-recursive.lisp naive FFT by simple recursion
• relative-error.lisp relative error
• log-factorial.lisp logarithm of factorial (logarithm of gamma function)

• bit-basher.lisp efficient operations on simple-bit-vector
• gray-code.lisp Gray code
• tzcount.lisp TZCNT operation
• logreverse.lisp bit-reversal operation

• bipartite-matching.lisp maximum bipartite matching (Ford-Fulkerson)
• hopcroft-karp.lisp maximum bipartite matching (Hopcroft-Karp)
• jonker-volgenant.lisp weighted bipartite matching (Jonker-Volgenant)
• gabow-edmonds.lisp maximum non-bipartite matching (Gabow-Edmonds)
• bipartite-p.lisp test of bipartiteness
• bron-kerbosch.lisp maximum clique
• ford-fulkerson.lisp maximum flow (Ford-Fulkerson algorithm)
• dinic.lisp maximum flow (Dinic's algorithm)
• lca.lisp lowest common anscestor (binary lifting)
• binary-lifting LCA and path queries on a static tree or forest with weighted edge or vertex (binary lifting)
• ssp.lisp minimum cost flow (SSP)
• topological-sort.lisp topological sort on DAG
• find-cycle.lisp (explicit) cycle detection
• euler-tour.lisp Euler tour of tree
• scc.lisp strongly connected component of directed graph (Tarjan's algorithm)
• 2sat.lisp 2SAT solver
• 2cc.lisp two-edge connected component of undirected graph
• tree-centroid.lisp centroid decomposition of tree
• chordal-graph.lisp recognition of graph chordality (maximum cardinality search); perfect elimination order
• diameter.lisp diameter of tree
• tree-hash.lisp hashing of rooted tree
• mo-tree.lisp Mo's algorithm for paths on tree (vertex query)
• random-graph.lisp fast generation of random adjacency matrices

• two-phase-simplex.lisp two-phase (dual-then-primal) simplex method for dense LP
• self-dual-simplex.lisp parametric self-dual simplex method for dense LP
• incremental-lp.lisp warm-start LP solver for dynamically added constraints, using dual simplex method for dense LP
• sparse-simplex.lisp two-phase (dual-then-primal) simplex method and self-dual simplex method for sparse LP
• ols.lisp ordinary least squares regression by Gaussian elimination

• complex-geometry.lisp some utilities for 2D geometry with complex number
• phase.lisp order by amplitude (atan)
• circumcenter.lisp circumcenter
• welzl.lisp smallest circle problem (Welzl's algorithm)
• convex-hull.lisp 2D convex hull (monotone chain algorithm)

• rolling-hash31.lisp 31-bit rolling hash
• rolling-hash62.lisp 62-bit rolling hash
• 2d-rolling-hash.lisp 2D 32-bit rolling hash
• triemap.lisp map structure with trie
• trie.lisp multiset structure with trie
• z-algorithm.lisp Z-algorithm

• read-line-into.lisp read-line into a given string
• buffered-read-line.lisp read-line into a recycled string
• read-fixnum.lisp faster read for fixnum
• read-bignum.lisp faster read for bignum
• write-double-float.lisp write double-float with fixed-point expression

• template.lisp template code
• mpfr.lisp header to load SB-MPFR
• with-cache.lisp memoization of function
• dotimes-unroll.lisp loop unrolling
• placeholder-syntax.lisp Clojure-style placeholder syntax

• integer-pack.lisp defstruct-like macro to deal with an integer as a structure of several integer slots
• increase-space.lisp This header runs another SBCL as external process and leaves the entire processing to it. (This ugly hack was invented to increase the stack size of SBCL on online judges.)
• compile-time-increase-space.lisp analogue of increase-space at compile time