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View the Project on GitHub Luzhiled/syakyo-library
#include "src/math/modular-arithmetic/small-mod-combination.hpp"
#pragma once #include "src/math/modular-arithmetic/modular-combinatorics.hpp" namespace luz { template < typename modint > class SmallModCombination { static constexpr auto mod = modint::get_mod(); Combinatorics< modint > mc; public: SmallModCombination(): mc(mod - 1) {} modint combination(isize n, isize r) { if (r < 0 or n < r) return 0; modint result(1); while (n) { result *= mc.combination(n % mod, r % mod); n /= mod; r /= mod; } return result; } modint C(isize n, isize r) { return combination(n, r); } }; } // namespace luz
#line 2 "src/math/modular-arithmetic/small-mod-combination.hpp" #line 2 "src/math/modular-arithmetic/modular-combinatorics.hpp" #line 2 "src/cpp-template/header/size-alias.hpp" #include <cstddef> namespace luz { using isize = std::ptrdiff_t; using usize = std::size_t; } #line 4 "src/math/modular-arithmetic/modular-combinatorics.hpp" #include <vector> namespace luz { template < typename mint > class Combinatorics { static usize bound; static std::vector< mint > fact, finv, inv; static void expand(usize n) { n += 1; if (fact.size() >= n) return; if (bound == 0) bound = 1; fact.resize(n, mint(1)); finv.resize(n, mint(1)); inv.resize(n, mint(1)); for (usize i = bound; i < n; i++) { fact[i] = fact[i - 1] * i; } finv.back() = mint(1) / fact.back(); for (usize i = n - 1; i >= bound; i--) { finv[i - 1] = finv[i] * i; } for (usize i = bound; i < n; i++) { inv[i] = finv[i] * fact[i - 1]; } bound = n; } public: explicit Combinatorics(usize n = 0) { expand(n); } static mint factorial(usize n) { expand(n); return fact[n]; } static mint factorial_inverse(usize n) { expand(n); return finv[n]; } static mint inverse(usize n) { expand(n); return inv[n]; } static mint permutation(isize n, isize r) { if (r < 0 or n < r) return 0; expand(n); return fact[n] * finv[n - r]; } static mint combination(isize n, isize r) { if (r < 0 or n < r) return 0; expand(n); return fact[n] * finv[r] * finv[n - r]; } static mint combination_with_repetitions(isize n, isize r) { if (n < 0 or r < 0) return 0; return (r ? combination(n + r - 1, r) : 1); } static mint P(isize n, isize r) { return permutation(n, r); } static mint C(isize n, isize r) { return combination(n, r); } static mint H(isize n, isize r) { return combination_with_repetitions(n, r); } }; template < typename mint > usize Combinatorics< mint >::bound = 0; template < typename mint > std::vector< mint > Combinatorics< mint >::fact = std::vector< mint >(); template < typename mint > std::vector< mint > Combinatorics< mint >::finv = std::vector< mint >(); template < typename mint > std::vector< mint > Combinatorics< mint >::inv = std::vector< mint >(); } // namespace luz #line 4 "src/math/modular-arithmetic/small-mod-combination.hpp" namespace luz { template < typename modint > class SmallModCombination { static constexpr auto mod = modint::get_mod(); Combinatorics< modint > mc; public: SmallModCombination(): mc(mod - 1) {} modint combination(isize n, isize r) { if (r < 0 or n < r) return 0; modint result(1); while (n) { result *= mc.combination(n % mod, r % mod); n /= mod; r /= mod; } return result; } modint C(isize n, isize r) { return combination(n, r); } }; } // namespace luz