🧪 bm.test.cpp

View this file on GitHub · Last update: 2026-07-27 05:29:51-07:00

Depends on

• bm.hpp
• modnum.hpp

Code

#include <catch2/catch_test_macros.hpp>

#include "bm.hpp"
#include "modnum.hpp"

using namespace std;

TEST_CASE("Berlekamp Massey", "[bm]") {
	using num = modnum<int(1e9)+7>;
	vector<num> S({0, 1, 1, 2, 3, 5, 8, 13});
	vector<num> tr = BerlekampMassey(S);
	REQUIRE(tr == vector<num>({num(1), num(1)}));
	num res = linearRec(S, tr, 1000);
	REQUIRE(res == num(517691607));
}

#include <catch2/catch_test_macros.hpp>
#include <bits/stdc++.h>
#line 2 "src/bm.test.cpp"

#line 3 "src/bm.hpp"

template <typename num>
std::vector<num> BerlekampMassey(const std::vector<num>& s) {
	int n = int(s.size()), L = 0, m = 0;
	std::vector<num> C(n), B(n), T;
	C[0] = B[0] = 1;

	num b = 1;
	for(int i = 0; i < n; i++) { ++m;
		num d = s[i];
		for (int j = 1; j <= L; j++) d += C[j] * s[i - j];
		if (d == 0) continue;
		T = C; num coef = d / b;
		for (int j = m; j < n; j++) C[j] -= coef * B[j - m];
		if (2 * L > i) continue;
		L = i + 1 - L; B = T; b = d; m = 0;
	}

	C.resize(L + 1); C.erase(C.begin());
	for (auto& x : C) {
		x = -x;
	}
	return C;
}

template <typename num>
num linearRec(const std::vector<num>& S, const std::vector<num>& tr, int64_t k) {
	int n = int(tr.size());
	assert(S.size() >= tr.size());

	auto combine = [&](std::vector<num> a, std::vector<num> b, bool e = false) {
		// multiply a * b * x^e
		std::vector<num> res(int(a.size()) + int(b.size()));
		for (int i = 0; i < int(a.size()); i++) {
			for (int j = 0; j < int(b.size()); j++) {
				res[i + j + e] += a[i] * b[j];
			}
		}
		for (int i = int(res.size())-1; i >= n; --i) {
			for (int j = 0; j < n; j++) {
				res[i - 1 - j] += res[i] * tr[j];
			}
		}
		res.resize(n);
		return res;
	};

	std::vector<num> pol(n);
	if (n > 0) pol[0] = num(1);

	assert(k >= 0);
	for (int i = 64 - 1 - (k == 0 ? 64 : __builtin_clzll(k)); i >= 0; i--) {
		pol = combine(pol, pol, (k >> i) & 1);
	}

	num res = 0;
	for (int i = 0; i < n; i++) res += pol[i] * S[i];
	return res;
}
#line 2 "src/modnum.hpp"

#line 9 "src/modnum.hpp"

template <typename T> T mod_inv_in_range(T a, T m) {
	// assert(0 <= a && a < m);
	T x = a, y = m;
	// abs coeff of a in x and y (they're always opposite sign)
	T vx = 1, vy = 0;
	bool swap = false;
	while (x) {
		T k = y / x;
		y %= x;
		vy += k * vx;
		std::swap(x, y);
		std::swap(vx, vy);
		swap ^= 1;
	}
	assert(y == 1);
	return swap ? vy : m - vy;
}

template <typename T> struct extended_gcd_result {
	T gcd;
	T coeff_a, coeff_b;
};
template <typename T> extended_gcd_result<T> extended_gcd(T a, T b) {
	T x = a, y = b;
	// coeff of a and b in x and y
	T ax = 1, ay = 0;
	T bx = 0, by = 1;
	while (x) {
		T k = y / x;
		y %= x;
		ay -= k * ax;
		by -= k * bx;
		std::swap(x, y);
		std::swap(ax, ay);
		std::swap(bx, by);
	}
	return {y, ay, by};
}

template <typename T> T mod_inv(T a, T m) {
	a %= m;
	a = a < 0 ? a + m : a;
	return mod_inv_in_range(a, m);
}

// Derives the boilerplate operator surface of a number type from its compound
// ops, ==, neg(), and inv().
// Bodies are only instantiated on use, so a type may omit some of the
// underlying pieces if the corresponding derived ops are never called.
template <typename Self>
struct num_ops {
	Self operator+ () const { return static_cast<const Self&>(*this); }
	Self operator- () const { return static_cast<const Self&>(*this).neg(); }

	friend Self operator ++ (Self& a, int) { Self r = a; ++a; return r; }
	friend Self operator -- (Self& a, int) { Self r = a; --a; return r; }
	friend Self operator + (const Self& a, const Self& b) { return Self(a) += b; }
	friend Self operator - (const Self& a, const Self& b) { return Self(a) -= b; }
	friend Self operator * (const Self& a, const Self& b) { return Self(a) *= b; }
	friend Self operator / (const Self& a, const Self& b) { return Self(a) /= b; }

	friend bool operator != (const Self& a, const Self& b) { return !(a == b); }

	friend Self neg(const Self& a) { return a.neg(); }
	friend Self inv(const Self& a) { return a.inv(); }
};

// Storage and arithmetic for numbers mod Self::MOD, as a reduced
// representative v in [0, MOD) of unsigned type V.
// The type provides static MOD (of type V), reduce (value -> representative),
// and *=;
// everything else is derived here, valid for any MOD up to V's full range
// (sums and differences are tracked mod 2^bits, so no headroom is needed).
// Hooks may be overridden in the type's own body (e.g. a faster += / -=).
template <typename Self, typename V>
struct mod_ops : num_ops<Self> {
	static_assert(std::unsigned_integral<V>);
	V v;

	struct is_reduced_tag {};

	mod_ops() : v(0) {}
	mod_ops(V v_, is_reduced_tag) : v(v_) { assert(v < Self::MOD); }
	template <std::integral I> mod_ops(I x) : v(Self::reduce(x)) {}

	static Self from_reduced(V v) { return Self(v, is_reduced_tag{}); }

	// A negative value reduces via its nonnegative complement: x = -1 - ~x.
	static V reduce(std::signed_integral auto x) {
		using U = std::make_unsigned_t<decltype(x)>;
		return x < 0 ? V(Self::MOD - 1 - Self::reduce(U(~x))) : Self::reduce(U(x));
	}

	explicit operator V() const { return v; }
	std::make_signed_t<V> balanced() const {
		return std::make_signed_t<V>(Self::MOD-v > v ? v : v - Self::MOD);
	}

	friend bool operator == (const Self& a, const Self& b) { return a.v == b.v; }
	friend std::ostream& operator << (std::ostream& out, const Self& n) { return out << n.v; }
	friend std::istream& operator >> (std::istream& in, Self& n) { int64_t v_; in >> v_; n = Self(v_); return in; }

	Self& operator ++ () {
		++v;
		if (v == Self::MOD) v = 0;
		return self();
	}
	Self& operator -- () {
		if (v == 0) v = Self::MOD;
		--v;
		return self();
	}
	Self& operator += (const Self& o) { v = Self::sub_mod_raw(v, Self::MOD - o.v); return self(); }
	Self& operator -= (const Self& o) { v = Self::sub_mod_raw(v, o.v); return self(); }
	Self& operator /= (const Self& o) { return self() *= o.inv(); }

	// Returns a - b mod MOD, for b in [0, MOD]; wraparound detects the underflow.
	static V sub_mod_raw(V a, V b) { return a < b ? a - b + Self::MOD : a - b; }

	Self neg() const { return from_reduced(v ? Self::MOD - v : 0); }
	Self inv() const { return from_reduced(mod_inv_in_range(v, Self::MOD)); }

private:
	Self& self() { return static_cast<Self&>(*this); }
};

template <auto MOD_> struct modnum : mod_ops<modnum<MOD_>, std::make_unsigned_t<decltype(MOD_)>> {
	using Self = modnum;
	static_assert(MOD_ > 0, "MOD must be positive");
	using V = std::make_unsigned_t<decltype(MOD_)>;
	static constexpr V MOD = V(MOD_);

	using base = mod_ops<modnum, V>;
	using base::base;
	using base::v;
	using base::reduce;

	static V reduce(std::unsigned_integral auto x) { return V(x % MOD); }

	explicit operator std::make_signed_t<V>() const
		requires (MOD <= V(std::numeric_limits<std::make_signed_t<V>>::max()))
	{
		return std::make_signed_t<V>(v);
	}

	Self& operator *= (const Self& o) {
		if constexpr (sizeof(V) <= 4) v = V(uint64_t(v) * o.v % MOD);
		else v = V(__uint128_t(v) * o.v % MOD);
		return *this;
	}
};

struct mod_goldilocks : mod_ops<mod_goldilocks, uint64_t> {
	using Self = mod_goldilocks;
	static constexpr uint64_t MOD = 0xffffffff00000001ull;
	static constexpr uint64_t EPS = -MOD;
	// We have 2^32 is a primitive 6th root of unity.
	// Note that omega_8 + omega_8^7 == 2^24 - 2^72 == sqrt(2)
	// We'll pick the root so that 2^24 - 2^72 is our primitive 384th root of unity.
	static constexpr uint64_t PRIMITIVE_ROOT = 2717;

	using base = mod_ops<mod_goldilocks, uint64_t>;
	using base::base;
	using base::reduce;
	mod_goldilocks() = default;
	mod_goldilocks(__int128_t a) : base(a < 0 ? uint64_t(MOD - 1 - __uint128_t(~a) % MOD) : uint64_t(__uint128_t(a) % MOD), is_reduced_tag{}) {}
	mod_goldilocks(__uint128_t a) : base(uint64_t(a % MOD), is_reduced_tag{}) {}

	// Avoids the division: any uint64_t is within MOD of reduced.
	static uint64_t reduce(std::unsigned_integral auto x) {
		static_assert(sizeof(x) <= 8);
		uint64_t a = x;
		return a >= MOD ? a - MOD : a;
	}

	// returns a-b, assuming -MOD <= a-b, e.g. b <= MOD
	static uint64_t sub_mod_raw(uint64_t a, uint64_t b) {
#if defined(__x86_64__)
		// TODO: We could try to write this using intrinsics, but GCC sometimes produces the wrong code.
		uint64_t res_wrapped = a;
		uint64_t adjustment = b;
		asm (
			// AT&T syntax: SRC DST
			"sub %[y], %[x]\n\t"
			// Trick from plonky2 implementation:
			// After sub, flag CF is set iff we underflowed. We want to correct by EPS == 2^32 - 1 iff C is set.
			// sbb (subtract with borrow) computes DST <- DST - SRC - CF
			// Thus, we can use the 32-bit form of sbb on a dummy register to load CF ? EPS : 0.
			// Here, we'll just reuse the original register holding b.
			"sbb %k[y], %k[y]\n\t"
			: [x] "+r"(res_wrapped),
			[y] "+r"(adjustment)
			:
			: "cc"
		);
#else
		uint64_t res_wrapped = a - b;
		uint64_t adjustment = (res_wrapped > a) ? EPS : 0;
#endif
		return res_wrapped - adjustment;
	}

	// Reduce lo + 2^64 * mi + 2^96 * hi, where hi <= MOD
	static uint64_t reduce_u160_raw(uint64_t lo, uint32_t mi, uint64_t hi) {
		// result = lo - hi + EPS * mi
		// 0 <= lo <= 2^64 - 1 = MOD + EPS - 1
		// 0 <= EPS * mi <= (2^32 - 1) * EPS = MOD - 1 - EPS
		// 0 <= hi <= MOD
		// -MOD <= lo - hi + EPS * mi <= 2*MOD-2
		// so we do have some leeway
		return sub_mod_raw(sub_mod_raw(lo, hi), MOD-(uint64_t(mi)<<32)+mi);
	}

	static uint64_t reduce_u128_raw(__uint128_t v) {
		uint64_t hi = uint64_t(v >> 64);
		uint64_t lo = uint64_t(v);
		uint32_t hi_hi = uint32_t(hi >> 32);
		uint32_t hi_lo = uint32_t(hi);
		return reduce_u160_raw(lo, hi_lo, hi_hi);
	}

	Self& operator *= (Self o) {
		v = reduce_u128_raw(__uint128_t(v) * __uint128_t(o.v));
		return *this;
	}
};

template <typename T> T power(T a, long long b) {
	assert(b >= 0);
	T r = 1; while (b) { if (b & 1) r *= a; b >>= 1; a *= a; } return r;
}

template <typename U, typename V> struct pairnum : num_ops<pairnum<U, V>> {
	using Self = pairnum;
	U u;
	V v;

	pairnum() : u(0), v(0) {}
	pairnum(long long val) : u(val), v(val) {}
	pairnum(const U& u_, const V& v_) : u(u_), v(v_) {}

	friend std::ostream& operator << (std::ostream& out, const Self& n) { return out << '(' << n.u << ',' << ' ' << n.v << ')'; }
	friend std::istream& operator >> (std::istream& in, Self& n) { long long val; in >> val; n = Self(val); return in; }

	friend bool operator == (const Self& a, const Self& b) { return a.u == b.u && a.v == b.v; }

	Self inv() const {
		return Self(u.inv(), v.inv());
	}
	Self neg() const {
		return Self(u.neg(), v.neg());
	}

	Self& operator ++ () {
		++u, ++v;
		return *this;
	}
	Self& operator -- () {
		--u, --v;
		return *this;
	}

	Self& operator += (const Self& o) {
		u += o.u;
		v += o.v;
		return *this;
	}
	Self& operator -= (const Self& o) {
		u -= o.u;
		v -= o.v;
		return *this;
	}
	Self& operator *= (const Self& o) {
		u *= o.u;
		v *= o.v;
		return *this;
	}
	Self& operator /= (const Self& o) {
		u /= o.u;
		v /= o.v;
		return *this;
	}
};

template <typename tag> struct dynamic_modnum : mod_ops<dynamic_modnum<tag>, uint32_t> {
	using Self = dynamic_modnum;
private:
	inline static uint32_t MOD_ = 0;
	inline static uint64_t BARRETT_M = 0;

public:
	// Make only the const-reference public, to force the use of set_mod
	static constexpr uint32_t const& MOD = MOD_;

	using base = mod_ops<dynamic_modnum, uint32_t>;
	using base::base;
	using base::v;
	using base::reduce;

	// Barret reduction taken from KACTL:
	/**
	 * Author: Simon Lindholm
	 * Date: 2020-05-30
	 * License: CC0
	 * Source: https://en.wikipedia.org/wiki/Barrett_reduction
	 * Description: Compute $a \% b$ about 5 times faster than usual, where $b$ is constant but not known at compile time.
	 * Returns a value congruent to $a \pmod b$ in the range $[0, 2b)$.
	 * Status: proven correct, stress-tested
	 * Measured as having 4 times lower latency, and 8 times higher throughput, see stress-test.
	 * Details:
	 * More precisely, it can be proven that the result equals 0 only if $a = 0$,
	 * and otherwise lies in $[1, (1 + a/2^64) * b)$.
	 */
	static void set_mod(int mod) {
		assert(mod > 0);
		MOD_ = uint32_t(mod);
		BARRETT_M = (uint64_t(-1) / MOD);
	}
	static uint32_t barrett_reduce_partial(uint64_t a) {
		return uint32_t(a - uint64_t((__uint128_t(BARRETT_M) * a) >> 64) * MOD);
	}
	static uint32_t barrett_reduce(uint64_t a) {
		int32_t res = int32_t(barrett_reduce_partial(a) - MOD);
		return uint32_t((res < 0) ? res + int32_t(MOD) : res);
	}

	struct mod_reader {
		friend std::istream& operator >> (std::istream& i, mod_reader) {
			int mod; i >> mod;
			Self::set_mod(mod);
			return i;
		}
	};
	static mod_reader MOD_READER() {
		return mod_reader();
	}

	static uint32_t reduce(std::unsigned_integral auto x) {
		static_assert(sizeof(x) <= 8);
		return barrett_reduce(x);
	}

	explicit operator int() const { return int(v); }

	Self& operator *= (const Self& o) {
		v = barrett_reduce(uint64_t(v) * o.v);
		return *this;
	}
};

template <typename T> struct mod_constraint {
	T v, mod;

	friend mod_constraint operator & (mod_constraint a, mod_constraint b) {
		if (a.mod < b.mod) std::swap(a, b);
		if (b.mod == 1) return a;

		extended_gcd_result<T> egcd = extended_gcd<T>(a.mod, b.mod);
		assert(a.v % egcd.gcd == b.v % egcd.gcd);

		T extra = b.v - a.v % b.mod;
		extra /= egcd.gcd;

		extra *= egcd.coeff_a;
		extra %= b.mod / egcd.gcd;
		extra += (extra < 0) ? b.mod / egcd.gcd : 0;

		return mod_constraint{
			a.v + extra * a.mod,
			a.mod * (b.mod / egcd.gcd)
		};
	}
};
#line 5 "src/bm.test.cpp"

using namespace std;

TEST_CASE("Berlekamp Massey", "[bm]") {
	using num = modnum<int(1e9)+7>;
	vector<num> S({0, 1, 1, 2, 3, 5, 8, 13});
	vector<num> tr = BerlekampMassey(S);
	REQUIRE(tr == vector<num>({num(1), num(1)}));
	num res = linearRec(S, tr, 1000);
	REQUIRE(res == num(517691607));
}

// clang-format off
// @formatter:off
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wpragmas"
#pragma GCC diagnostic ignored "-Wunknown-warning-option"
#pragma GCC diagnostic ignored "-Wmisleading-indentation"
#pragma GCC diagnostic ignored "-Wmultistatement-macros"
#include <bits/stdc++.h>
#include <catch2/catch_test_macros.hpp>
// src/bm.hpp
template<typename num>
std::vector<num>BerlekampMassey(const std::vector<num>&s){
int n=int(s.size()),L=0,m=0;
std::vector<num>C(n),B(n),T;
C[0]=B[0]=1;
num b=1;
for(int i=0;i<n;i++){++m;
num d=s[i];
for(int j=1;j<=L;j++)d+=C[j]*s[i-j];
if(d==0)continue;
T=C;num coef=d/b;
for(int j=m;j<n;j++)C[j]-=coef*B[j-m];
if(2*L>i)continue;
L=i+1-L;B=T;b=d;m=0;
}
C.resize(L+1);C.erase(C.begin());
for(auto&x:C){
x=-x;
}
return C;
}
template<typename num>
num linearRec(const std::vector<num>&S,const std::vector<num>&tr,int64_t k){
int n=int(tr.size());
assert(S.size()>=tr.size());
auto combine=[&](std::vector<num>a,std::vector<num>b,bool e=false){
std::vector<num>res(int(a.size())+int(b.size()));
for(int i=0;i<int(a.size());i++){
for(int j=0;j<int(b.size());j++){
res[i+j+e]+=a[i]*b[j];
}
}
for(int i=int(res.size())-1;i>=n;--i){
for(int j=0;j<n;j++){
res[i-1-j]+=res[i]*tr[j];
}
}
res.resize(n);
return res;
};
std::vector<num>pol(n);
if(n>0)pol[0]=num(1);
assert(k>=0);
for(int i=64-1-(k==0?64:__builtin_clzll(k));i>=0;i--){
pol=combine(pol,pol,(k>>i)&1);
}
num res=0;
for(int i=0;i<n;i++)res+=pol[i]*S[i];
return res;
}
// src/modnum.hpp
template<typename T>T mod_inv_in_range(T a,T m){
T x=a,y=m;
T vx=1,vy=0;
bool swap=false;
while(x){
T k=y/x;
y%=x;
vy+=k*vx;
std::swap(x,y);
std::swap(vx,vy);
swap^=1;
}
assert(y==1);
return swap?vy:m-vy;
}
template<typename T>struct extended_gcd_result{
T gcd;
T coeff_a,coeff_b;
};
template<typename T>extended_gcd_result<T>extended_gcd(T a,T b){
T x=a,y=b;
T ax=1,ay=0;
T bx=0,by=1;
while(x){
T k=y/x;
y%=x;
ay-=k*ax;
by-=k*bx;
std::swap(x,y);
std::swap(ax,ay);
std::swap(bx,by);
}
return{y,ay,by};
}
template<typename T>T mod_inv(T a,T m){
a%=m;
a=a<0?a+m:a;
return mod_inv_in_range(a,m);
}
template<typename Self>
struct num_ops{
Self operator+()const{return static_cast<const Self&>(*this);}
Self operator-()const{return static_cast<const Self&>(*this).neg();}
friend Self operator++(Self&a,int){Self r=a;++a;return r;}
friend Self operator--(Self&a,int){Self r=a;--a;return r;}
friend Self operator+(const Self&a,const Self&b){return Self(a)+=b;}
friend Self operator-(const Self&a,const Self&b){return Self(a)-=b;}
friend Self operator*(const Self&a,const Self&b){return Self(a)*=b;}
friend Self operator/(const Self&a,const Self&b){return Self(a)/=b;}
friend bool operator!=(const Self&a,const Self&b){return!(a==b);}
friend Self neg(const Self&a){return a.neg();}
friend Self inv(const Self&a){return a.inv();}
};
template<typename Self,typename V>
struct mod_ops:num_ops<Self>{
static_assert(std::unsigned_integral<V>);
V v;
struct is_reduced_tag{};
mod_ops():v(0){}
mod_ops(V v_,is_reduced_tag):v(v_){assert(v<Self::MOD);}
template<std::integral I>mod_ops(I x):v(Self::reduce(x)){}
static Self from_reduced(V v){return Self(v,is_reduced_tag{});}
static V reduce(std::signed_integral auto x){
using U=std::make_unsigned_t<decltype(x)>;
return x<0?V(Self::MOD-1-Self::reduce(U(~x))):Self::reduce(U(x));
}
explicit operator V()const{return v;}
std::make_signed_t<V>balanced()const{
return std::make_signed_t<V>(Self::MOD-v>v?v:v-Self::MOD);
}
friend bool operator==(const Self&a,const Self&b){return a.v==b.v;}
friend std::ostream&operator<<(std::ostream&out,const Self&n){return out<<n.v;}
friend std::istream&operator>>(std::istream&in,Self&n){int64_t v_;in>>v_;n=Self(v_);return in;}
Self&operator++(){
++v;
if(v==Self::MOD)v=0;
return self();
}
Self&operator--(){
if(v==0)v=Self::MOD;
--v;
return self();
}
Self&operator+=(const Self&o){v=Self::sub_mod_raw(v,Self::MOD-o.v);return self();}
Self&operator-=(const Self&o){v=Self::sub_mod_raw(v,o.v);return self();}
Self&operator/=(const Self&o){return self()*=o.inv();}
static V sub_mod_raw(V a,V b){return a<b?a-b+Self::MOD:a-b;}
Self neg()const{return from_reduced(v?Self::MOD-v:0);}
Self inv()const{return from_reduced(mod_inv_in_range(v,Self::MOD));}
private:
Self&self(){return static_cast<Self&>(*this);}
};
template<auto MOD_>struct modnum:mod_ops<modnum<MOD_>,std::make_unsigned_t<decltype(MOD_)>>{
using Self=modnum;
static_assert(MOD_>0,"MOD must be positive");
using V=std::make_unsigned_t<decltype(MOD_)>;
static constexpr V MOD=V(MOD_);
using base=mod_ops<modnum,V>;
using base::base;
using base::v;
using base::reduce;
static V reduce(std::unsigned_integral auto x){return V(x%MOD);}
explicit operator std::make_signed_t<V>()const
requires(MOD<=V(std::numeric_limits<std::make_signed_t<V>>::max()))
{
return std::make_signed_t<V>(v);
}
Self&operator*=(const Self&o){
if constexpr(sizeof(V)<=4)v=V(uint64_t(v)*o.v%MOD);
else v=V(__uint128_t(v)*o.v%MOD);
return*this;
}
};
struct mod_goldilocks:mod_ops<mod_goldilocks,uint64_t>{
using Self=mod_goldilocks;
static constexpr uint64_t MOD=0xffffffff00000001ull;
static constexpr uint64_t EPS=-MOD;
static constexpr uint64_t PRIMITIVE_ROOT=2717;
using base=mod_ops<mod_goldilocks,uint64_t>;
using base::base;
using base::reduce;
mod_goldilocks()=default;
mod_goldilocks(__int128_t a):base(a<0?uint64_t(MOD-1-__uint128_t(~a)%MOD):uint64_t(__uint128_t(a)%MOD),is_reduced_tag{}){}
mod_goldilocks(__uint128_t a):base(uint64_t(a%MOD),is_reduced_tag{}){}
static uint64_t reduce(std::unsigned_integral auto x){
static_assert(sizeof(x)<=8);
uint64_t a=x;
return a>=MOD?a-MOD:a;
}
static uint64_t sub_mod_raw(uint64_t a,uint64_t b){
#if defined(__x86_64__)
uint64_t res_wrapped=a;
uint64_t adjustment=b;
asm(
"sub %[y], %[x]\n\t"
"sbb %k[y], %k[y]\n\t"
:[x]"+r"(res_wrapped),
[y]"+r"(adjustment)
:
:"cc"
);
#else
uint64_t res_wrapped=a-b;
uint64_t adjustment=(res_wrapped>a)?EPS:0;
#endif
return res_wrapped-adjustment;
}
static uint64_t reduce_u160_raw(uint64_t lo,uint32_t mi,uint64_t hi){
return sub_mod_raw(sub_mod_raw(lo,hi),MOD-(uint64_t(mi)<<32)+mi);
}
static uint64_t reduce_u128_raw(__uint128_t v){
uint64_t hi=uint64_t(v>>64);
uint64_t lo=uint64_t(v);
uint32_t hi_hi=uint32_t(hi>>32);
uint32_t hi_lo=uint32_t(hi);
return reduce_u160_raw(lo,hi_lo,hi_hi);
}
Self&operator*=(Self o){
v=reduce_u128_raw(__uint128_t(v)*__uint128_t(o.v));
return*this;
}
};
template<typename T>T power(T a,long long b){
assert(b>=0);
T r=1;while(b){if(b&1)r*=a;b>>=1;a*=a;}return r;
}
template<typename U,typename V>struct pairnum:num_ops<pairnum<U,V>>{
using Self=pairnum;
U u;
V v;
pairnum():u(0),v(0){}
pairnum(long long val):u(val),v(val){}
pairnum(const U&u_,const V&v_):u(u_),v(v_){}
friend std::ostream&operator<<(std::ostream&out,const Self&n){return out<<'('<<n.u<<','<<' '<<n.v<<')';}
friend std::istream&operator>>(std::istream&in,Self&n){long long val;in>>val;n=Self(val);return in;}
friend bool operator==(const Self&a,const Self&b){return a.u==b.u&&a.v==b.v;}
Self inv()const{
return Self(u.inv(),v.inv());
}
Self neg()const{
return Self(u.neg(),v.neg());
}
Self&operator++(){
++u,++v;
return*this;
}
Self&operator--(){
--u,--v;
return*this;
}
Self&operator+=(const Self&o){
u+=o.u;
v+=o.v;
return*this;
}
Self&operator-=(const Self&o){
u-=o.u;
v-=o.v;
return*this;
}
Self&operator*=(const Self&o){
u*=o.u;
v*=o.v;
return*this;
}
Self&operator/=(const Self&o){
u/=o.u;
v/=o.v;
return*this;
}
};
template<typename tag>struct dynamic_modnum:mod_ops<dynamic_modnum<tag>,uint32_t>{
using Self=dynamic_modnum;
private:
inline static uint32_t MOD_=0;
inline static uint64_t BARRETT_M=0;
public:
static constexpr uint32_t const&MOD=MOD_;
using base=mod_ops<dynamic_modnum,uint32_t>;
using base::base;
using base::v;
using base::reduce;
static void set_mod(int mod){
assert(mod>0);
MOD_=uint32_t(mod);
BARRETT_M=(uint64_t(-1)/MOD);
}
static uint32_t barrett_reduce_partial(uint64_t a){
return uint32_t(a-uint64_t((__uint128_t(BARRETT_M)*a)>>64)*MOD);
}
static uint32_t barrett_reduce(uint64_t a){
int32_t res=int32_t(barrett_reduce_partial(a)-MOD);
return uint32_t((res<0)?res+int32_t(MOD):res);
}
struct mod_reader{
friend std::istream&operator>>(std::istream&i,mod_reader){
int mod;i>>mod;
Self::set_mod(mod);
return i;
}
};
static mod_reader MOD_READER(){
return mod_reader();
}
static uint32_t reduce(std::unsigned_integral auto x){
static_assert(sizeof(x)<=8);
return barrett_reduce(x);
}
explicit operator int()const{return int(v);}
Self&operator*=(const Self&o){
v=barrett_reduce(uint64_t(v)*o.v);
return*this;
}
};
template<typename T>struct mod_constraint{
T v,mod;
friend mod_constraint operator&(mod_constraint a,mod_constraint b){
if(a.mod<b.mod)std::swap(a,b);
if(b.mod==1)return a;
extended_gcd_result<T>egcd=extended_gcd<T>(a.mod,b.mod);
assert(a.v%egcd.gcd==b.v%egcd.gcd);
T extra=b.v-a.v%b.mod;
extra/=egcd.gcd;
extra*=egcd.coeff_a;
extra%=b.mod/egcd.gcd;
extra+=(extra<0)?b.mod/egcd.gcd:0;
return mod_constraint{
a.v+extra*a.mod,
a.mod*(b.mod/egcd.gcd)
};
}
};
// src/bm.test.cpp
using namespace std;
TEST_CASE("Berlekamp Massey","[bm]"){
using num=modnum<int(1e9)+7>;
vector<num>S({0,1,1,2,3,5,8,13});
vector<num>tr=BerlekampMassey(S);
REQUIRE(tr==vector<num>({num(1),num(1)}));
num res=linearRec(S,tr,1000);
REQUIRE(res==num(517691607));
}
#pragma GCC diagnostic pop
// clang-format on
// @formatter:on

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