NTT 小记

数论来力……证明之类的也许会大挂。

或者其实还好,在参考别人的证明思路之后。

Pre

注意到 FFT 中需要复数计算,原因在于涉及到了单位复数根。

有没有替代品?复数域(这是包含实数和虚数的)内暂时没有。

不过我们可以考虑在模意义下找一个。

阶与原根

下面 p 为模数。

对于一个正整数 p,能满足 gk1(modp) 的最小 kgp 的阶,记作 δp(g)

阶的一条性质:若 gk1(modp),则 δp(g)k

证明则是把 k 除掉 δp(g),得到 gqδp(g)+r1(modp),然后 (gδp(g))q1(modp),所以若 r0 就和阶的最小性矛盾。

对于一个正整数 p,存在一个 g 使得 gcd(g,p)=1δp(g)=φ(p),则 g 称作模 p 的原根。

由于我们要用到不同 n 下的单位根,我们考虑给原根也配个类似的出来:gn=gp1n,其中 np1,此时 gnp 的一个原根性质的东西,且刚好和这个 ωn 意义类似。

证明的话考虑 gk,其阶为 p1gcd(p1,k)(原因考虑欧拉定理,这里也可以说是费马小定理,把这玩意儿弄到上界),然后我们想要 n 是这个原根的阶,就可以考虑构造;发现 p1gcd(p1,(p1)/n)=p1(p1)/n=n,所以就取 gp1n

如果 np1,发现要求 p1gcd(p1,x)=n,也就是说 gcd(p1,x)=p1n,那这玩意儿就不是整数了,显然不合法。

然后我们看这个 gn,它满足单位根的性质吗?

  1. ωn0,,ωnn1 两两不同。

    单位根定义,显然。

    证明考虑取 gnignj(modp),然后两边做商发现违背阶的最小性。

  2. ωdndk=ωnk

    消去引理。同理,和单位根那一模一样。

  3. {(ωn0)2,,(ωnn1)2}={ωn/20,,ωn/2n/21}

    折半引理,这里比较棘手。

    首先说明 gnk=gnk+n/2,考虑两边分别平分,有 gn2k=gn2k+n。显然其中 gnn=(gp1n)n=gp1=1,故成立。

    然后就说好了,这玩意儿显然了,也不棘手。

  4. k=0n1(ωnd)k=(ωnd)n1ωnd1,要求 dn

    有没有可能我们最先在整数域上学的等比数列这玩意儿。

现在我们说明了在模意义下原根跟单位根有一样好的性质,也能拿来算多项式乘法.

而这个东西由于涉及到上面一堆数学,于是就成了 NTT(快速数论变换)。

式子基本一致,把 ωn 换成 gn 即可。

注意我们要求 np1,而 n=2k,kN+,所以你随便搞个 p12k 倍数的模数就好了,如典中典的 998244353=217×17×7+1,且存在一个原根 g=3(当然你也可以取 g=114514

代码咕了。

qL 代码封好了,放一个跑不赢 FFT 的垃圾供大家欣赏:

#include<cstdio>
#include<utility>
#include<cstdlib>
#include<type_traits>
#include<array>
/**
 * 写得死烂,又长又慢。
 * Author:qL
 * todo:
 * Better modInt
 * frac
 * More Poly
 * fix bug of radix_sort
 * new IO
*/
namespace QL{
	/**
	 * 图方便用的
	*/
	namespace{
		using ll=long long;
		using ull=unsigned long long;
		using uint=unsigned int;
		using db=double;
		using ld=long double;
#if _GLIBCXX_USE_INT128
		using lll=__int128;
		using ulll=unsigned __int128;
#else
		using lll=long long;
		using ulll=unsigned long long;
#endif
#if _GLIBCXX_NUMERIC&&(__cplusplus>=201703L)
		template<typename _Tp>
		constexpr _Tp Inf=std::numeric_limits<_Tp>::max()/2;
#else
		constexpr int Inf=0x3f3f3f3f;
		constexpr long long llInf=0x3f3f3f3f3f3f3f3f;
		constexpr double dbInf=1e17;
		constexpr long double ldInf=1e22;
#endif
#ifndef _GLIBCXX_CMATH
	#define sqrt __builtin_sqrt
	#define sqrtf __builtin_sqrtf
	#define sqrtl __builtin_sqrtl
	#define ceil __builtin_ceil
	#define ceilf __builtin_ceilf
	#define ceill __builtin_ceill
	#define floor __builtin_floor
	#define floorf __builtin_floorf
	#define floorl __builtin_floorl
	#define log2 __builtin_log2
	#define log __builtin_log
	#define cos __builtin_cos
	#define sin __builtin_sin
	#define tan __builtin_tan
	#define acos __builtin_acos
#endif
#ifndef _GLIBCXX_CSTRING
	#define memset __builtin_memset
	#define memcpy __builtin_memcpy
	#define strlen __builtin_strlen
	#define strcmp __builtin_strcmp
#endif
#ifndef _GLIBCXX_CSTDIO
	#define fwrite __builtin_fwrite
	#define putchar __builtin_putchar
	#define fputc __builtin_fputc
	#define fputs __builtin_fputs
#endif
#ifndef likely
	#define likely(x) __builtin_expect(!!(x),1)
#endif
#ifndef unlikely
	#define unlikely(x) __builtin_expect(!!(x),0)
#endif
	}
	/**
	 * 不想多加头文件了……
	*/
	namespace Error{
		constexpr void make_re(int _seed_=114514){
			std::exit(_seed_);
		}
#ifndef _GLIBCXX_CASSERT
		constexpr bool assert(bool x,const char *reason){
			if(unlikely(!x)){
				fputs(reason,stderr);
				fputs(reason,stdout);
				make_re();
			}
			return false;
		}
		constexpr bool assert(bool x,char *reason){
			return assert(x,const_cast<const char *>(reason));
		}
		constexpr bool assert(bool x){
			if(unlikely(!x)){
				fputs("Assert: RE",stderr);
				fputs("Assert: RE",stdout);
				make_re();
			}
			return false;
		}
#endif
	}
}
namespace QL{
	/**
	 * 这坨代码最让人难以理解的地方:没逝乱靠元编程库
	*/
	namespace Traits_Tools{
		template<typename _Tp>
		class has_member_swap{
		private:
			template<typename T>
			static auto Check(void)->decltype(std::declval<T>().swap(),std::true_type());
			template<typename T>
			static std::false_type Check(...);
		public:
			enum{value=std::is_same<decltype(Check<_Tp>(nullptr)),std::true_type>::value};
		};
		#define Operator_Check_Helper(name,opt) \
				template<typename _Tp1,typename _Tp2> \
				class has_operator_##name{ \
				private: \
					template<typename T1,typename T2> \
					static auto Check(void)->decltype(std::declval<T1,T2>().operator opt (),std::true_type()); \
					template<typename T1,typename T2> \
					static std::false_type Check(...); \
				public: \
					enum{value=std::is_same<decltype(Check<_Tp1,_Tp2>(nullptr)),std::true_type>::value}; \
				};
		Operator_Check_Helper(plus,+)
		Operator_Check_Helper(subtract,-)
		Operator_Check_Helper(multiply,*)
		Operator_Check_Helper(divide,/)
		Operator_Check_Helper(mod,%)
		Operator_Check_Helper(and,&)
		Operator_Check_Helper(or,|)
		Operator_Check_Helper(xor,^)
		#undef Operator_Check_Helper
		#define Is_Type_Helper(type) \
		template<typename _Tp> \
		constexpr bool is_##type =false; \
		template<> \
		constexpr bool is_##type < type > =true;
		Is_Type_Helper(bool)
		Is_Type_Helper(char)
		#undef Is_Type_Helper
		template<typename _Tp,
		typename std::enable_if<!is_bool<_Tp>&&std::is_integral<_Tp>::value>::type* =nullptr>
		struct to_signed_type;
		#define To_Signed_Helper(type) \
		template<> \
		struct to_signed_type< unsigned type >{ \
			using signed_type= type ; \
		}; \
		template<> \
		struct to_signed_type < type >{ \
			using signed_type= type; \
		};
		To_Signed_Helper(int)
		To_Signed_Helper(long long)
		#undef To_Signed_Helper
		template<typename _Tp,
		typename std::enable_if<!is_bool<_Tp>&&std::is_integral<_Tp>::value>::type* =nullptr>
		struct to_unsigned_type;
		#define To_Unsigned_Helper(type) \
		template<> \
		struct to_unsigned_type< type >{ \
			using unsigned_type=unsigned type; \
		}; \
		template<> \
		struct to_unsigned_type< unsigned type >{ \
			using unsigned_type=unsigned type; \
		};
		To_Unsigned_Helper(int)
		To_Unsigned_Helper(long long)
		#undef To_Unsigned_Helper
		template<typename _Tp,
		typename std::enable_if<!is_bool<_Tp>&&!is_char<_Tp>&&std::is_integral<_Tp>::value>::type* =nullptr>
		struct to_upper_type;
		#define To_Upper_Helper(type,upper) \
		template<> \
		struct to_upper_type< type >{ \
			using unsigned_type=upper; \
		}; \
		template<> \
		struct to_upper_type< u##type >{ \
			using unsigned_type=u##upper; \
		};
		To_Upper_Helper(int,ll)
		To_Upper_Helper(ll,lll)
		#undef To_Upper_Helper
	}
}
namespace QL{
	namespace rel_ops{
		namespace Calc_Self{
			#define Calc_Self_Helper(opt) \
			template<typename _Tp1,typename _Tp2> \
			constexpr _Tp1 &operator opt##=(_Tp1 &lhs,const _Tp2 &rhs){ \
				return lhs=(lhs opt rhs); \
			}
			Calc_Self_Helper(+)
			Calc_Self_Helper(-)
			Calc_Self_Helper(*)
			Calc_Self_Helper(/)
			Calc_Self_Helper(%)
			Calc_Self_Helper(&)
			Calc_Self_Helper(|)
			Calc_Self_Helper(^)
			#undef Calc_Self_Helper
		}
		namespace Compare{
			template<typename _Tp1,typename _Tp2>
			constexpr bool operator!=(const _Tp1 &lhs,const _Tp2 &rhs){
				return !(lhs==rhs);
			}
			template<typename _Tp1,typename _Tp2>
			constexpr bool operator<=(const _Tp1 &lhs,const _Tp2 &rhs){
				return (lhs==rhs)||(lhs<rhs);
			}
			template<typename _Tp1,typename _Tp2>
			constexpr bool operator>(const _Tp1 &lhs,const _Tp2 &rhs){
				return !((lhs==rhs)||(lhs<rhs));
			}
			template<typename _Tp1,typename _Tp2>
			constexpr bool operator>=(const _Tp1 &lhs,const _Tp2 &rhs){
				return !(lhs<rhs);
			}
		}
	}
}
namespace QL{
	namespace Base_Tools{
		template<typename _Tp>
		static constexpr std::size_t integer_length=sizeof(_Tp)*10/sizeof(int);
		bool is_space(char ch){
			return ch==' ';
		}
		bool is_eoln(char ch){
#if (linux||__linux__||__linux)
			return ch=='\n'||ch=='\r';
#else
			return ch=='\n';
#endif
		}
		bool is_blank(char ch){
			return is_space(ch)||is_eoln(ch);
		}
		bool is_digit(char ch){
			switch(ch){
				case '0' ... '9': return true;
				default: return false;
			}
		}
		bool is_eof(char ch){
			return ch==EOF;
		}
	}
	namespace IO{
		using Base_Tools::integer_length;
		using Base_Tools::is_digit;
		using Base_Tools::is_space;
		using Base_Tools::is_eoln;
		using Base_Tools::is_blank;
		using Base_Tools::is_eof;
		/**
		 * fread+fwrite,-DLOACL for debug
		 * support:integer,floating,string,...
		 * todo:other
 		*/
		class IOstream{
		protected:
			using LIST=std::initializer_list<int>;
#ifndef LOCAL
			std::FILE *IN;
			std::FILE *OUT;
			static constexpr int SIZE=1<<15;
			char buf[SIZE]{},*p1{buf},*p2{buf},obuf[SIZE]{},*p3{obuf};
		public:
			char pull(){return p1==p2&&(p2=(p1=buf)+fread(buf,1,SIZE,IN),p1==p2)?(Ch=EOF):*p1++;}
			void push(char ch){((p3-obuf)==SIZE&&(flush(false),0)),*p3++=ch;}
			template<std::size_t L>
			std::FILE *set_in(const char (&name)[L]){
				static char in[L+5]={};
				std::sprintf(in,"%s.in",name);
				return std::fopen(in,"r");
			}
			template<std::size_t L>
			std::FILE *set_out(const char (&name)[L]){
				static char out[L+5];
				std::sprintf(out,"%s.out",name);
				return std::fopen(out,"w");
			}
#else
		protected:
		public:
			char pull(){return std::getchar();}
			void push(char ch){putchar(ch);}
			void err(char ch){fputc(ch,stderr);}
			template<std::size_t L>
			void set_in(const char(&name)[L]){
				static char in[L+5]={};
				std::sprintf(in,"%s.in",name);
				std::freopen(in,"r",stdin);
			}
			template<std::size_t L>
			void set_out(const char(&name)[L]){
				static char out[L+5];
				std::sprintf(out,"%s.out",name);
				std::freopen(out,"w",stdout);
			}
#endif
		public:
#ifndef LOCAL
			IOstream():IN{stdin},OUT{stdout},buf{},p1{buf},p2{buf},obuf{},p3{obuf},Ch{'\n'},outchar{&IO::IOstream::push}{}
			template<std::size_t L>
			IOstream(const char(&name)[L]):IN{set_in(name)},OUT{set_out(name)},buf{},p1{buf},p2{buf},obuf{},p3{obuf},Ch{'\n'},outchar{&IO::IOstream::push}{}
			template<std::size_t L>
			IOstream(const char(&name)[L],bool in,bool out):IN{in?set_in(name):stdin},OUT{out?set_out(name):stdout},buf{},p1{buf},p2{buf},obuf{},p3{obuf},Ch{'\n'},outchar{&IO::IOstream::push}{}
			template<std::size_t L>
			IOstream(char(&name)[L]):IN{set_in(name)},OUT{set_out(name)},buf{},p1{buf},p2{buf},obuf{},p3{obuf},Ch{'\n'},outchar{&IO::IOstream::push}{}
			template<std::size_t L>
			IOstream(char(&name)[L],bool in,bool out):IN{in?set_in(name):stdin},OUT{out?set_out(name):stdout},buf{},p1{buf},p2{buf},obuf{},p3{obuf},Ch{'\n'},outchar{&IO::IOstream::push}{}
			~IOstream(){flush();}
			void flush(bool _flush_=false){
				if(likely(p3!=obuf))
					fwrite(obuf,1,p3-obuf,OUT),p3=obuf;
				if(_flush_) std::fflush(stdout);
			}
#else
			IOstream(){}
			template<std::size_t L>
			IOstream(const char(&name)[L]):Ch{'\n'}{reset_stdin(name),reset_stdout(name);}
			template<std::size_t L>
			IOstream(const char(&name)[L],bool in,bool out):Ch{'\n'}{in&&(reset_stdin(name),0),out&&(reset_stdout(name),0);}
			template<std::size_t L>
			IOstream(char(&name)[L]):Ch{'\n'}{reset_stdin(name),reset_stdout(name);}
			template<std::size_t L>
			IOstream(char(&name)[L],bool in,bool out):Ch{'\n'}{in&&(reset_stdin(name),0),out&&(reset_stdout(name),0);}
			void flush(){std::fflush(stdout);}
#endif
			template<typename T>
			T read(){
				T x;
				read(x);
				return x;
			}
protected:
			char Ch='\n';
public:
			bool eof(void)const{
				return Ch==EOF;
			}
			template<typename T>
			void read(T &&x,typename std::enable_if<std::is_integral<T>::value,void>::type* =nullptr,typename std::enable_if<std::is_signed<T>::value,void>::type* =nullptr){
				x=0;bool flag=0;
				for(;!is_digit(Ch)&&!is_eof(Ch);Ch=pull()) if(Ch=='-') flag=1;
				if(is_eof(Ch)) return;
				if(flag) for(;is_digit(Ch);Ch=pull()) x=x*10-(Ch&15);
				else for(;is_digit(Ch);Ch=pull()) x=x*10+(Ch&15);
			}
			template<typename T>
			void read(T &&x,typename std::enable_if<std::is_integral<T>::value,void>::type* =nullptr,typename std::enable_if<std::is_unsigned<T>::value,void>::type* =nullptr){
				x=0;
				for(;!is_digit(Ch)&&!is_eof(Ch);Ch=pull());
				if(is_eof(Ch)) return;
				for(;is_digit(Ch);Ch=pull()) x=x*10+(Ch&15);
			}
			void read(char *str){
				for(;is_blank(Ch);Ch=pull());
				if(is_eof(Ch)) return (void)(*str='\0');
				for(;!is_blank(Ch)&&!is_eof(Ch);Ch=pull()) *str++=Ch;
				*str='\0';
			}
			void read(char &c){
				c=Ch;
				for(;is_blank(c)&&!is_eof(c);c=pull());
				if(is_eof(c)) return;
				Ch=pull();
			}
			void read(bool &x){
				for(;Ch!='0'&&Ch!='1'&&!is_eof(Ch);Ch=pull());
				if(is_eof(Ch)) return void(x=false);
				x=Ch=='1';
				Ch=pull();
			}
			template<typename T>
			void read(T &&x,typename std::enable_if<std::is_floating_point<T>::value,void*>::type* =nullptr){
				static char str[114];
				read(str);
				x=std::atof(str);
			}
			template<typename T>
			void read(T &x){read(std::move(x));}
		protected:
			void(IOstream::*outchar)(char)=&IO::IOstream::push;
			template<typename T>
			void out(T x,typename std::enable_if<std::is_integral<T>::value,void>::type* =nullptr,typename std::enable_if<std::is_signed<T>::value,void>::type* =nullptr){
				static char sta[integer_length<T>];
				int top=0;
				if(x<0){
					(this->*outchar)('-');
					do sta[top++]=((-x)%10)|48,x/=10;
					while(x);
				}
				else{
					do sta[top++]=(x%10)|48,x/=10;
					while(x);
				}
				while(top) (this->*outchar)(sta[--top]);
			}
			template<typename T>
			void out(T x,typename std::enable_if<std::is_integral<T>::value,void>::type* =nullptr,typename std::enable_if<std::is_unsigned<T>::value,void>::type* =nullptr){
				static char sta[integer_length<T>];
				int top=0;
				do sta[top++]=(x%10)|48,x/=10;
				while(x);
				while(top) (this->*outchar)(sta[--top]);
			}
			void out(bool x){(this->*outchar)(x?'1':'0');}
			void out(char x){(this->*outchar)(x);}
			void out(char *str){
				out(reinterpret_cast<const char *>(str));
			}
			void out(const char *str){
				while(*str!='\0') (this->*outchar)(*str++);
			}
			/**
			 * ssprintf is awful...
			 */
			void out(float x){
				static char str[114];
				std::sprintf(str,"%f",x);
				out(str);
			}
			void out(double x){
				static char str[114];
				std::sprintf(str,"%f",x);
				out(str);
			}
			void out(long double x){
				static char str[114];
				std::sprintf(str,"%Lf",x);
				out(str);
			}
			void out(std::pair<int,float> x){
				static char str[114],opt[10];
				std::sprintf(opt,"%%.%df",x.first);
				std::sprintf(str,opt,x.second);
				out(str);
			}
			void out(std::pair<int,double> x){
				static char str[114],opt[10];
				std::sprintf(opt,"%%.%df",x.first);
				std::sprintf(str,opt,x.second);
				out(str);
			}
			void out(std::pair<int,long double> x){
				static char str[114],opt[10];
				std::sprintf(opt,"%%.%dLf",x.first);
				std::sprintf(str,opt,x.second);
				out(str);
			}
			void set_std_out(){outchar=&IO::IOstream::push;}
#ifdef LOCAL
			void set_err_out(){outchar=&IO::IOstream::err;}
#endif
		public:
			template<typename...Args>
			void read(Args &&...args){(void)LIST{(read(args),0)...};}
			template<typename...Args>
			void write(Args...args){set_std_out(),(void)LIST{(out(args),0)...};}
			template<typename...Args>
			void writeln(Args...args){write(args...),push('\n');}
#ifdef LOCAL
			template<typename...Args>
			void error(Args...args){set_err_out(),(void)LIST{(out(args),0)...};}
			template<typename...Args>
			void errorln(Args...args){error(args...),err('\n');}
#endif
		};
		IOstream lq;
	}
}
namespace QL{
	namespace Base_Tools{
		template<typename _Tp1,typename _Tp2>
		constexpr auto min(_Tp1 x,_Tp2 y){
			return x<y?x:y;
		}
		template<typename _Tp,typename ...Args>
		constexpr auto min(_Tp x,Args ...args){
			return min(x,min(args...));
		}
		template<typename _Tp1,typename _Tp2>
		constexpr auto max(_Tp1 x,_Tp2 y){
			return y<x?x:y;
		}
		template<typename _Tp,typename ...Args>
		constexpr auto max(_Tp x,Args ...args){
			return max(x,max(args...));
		}
		template<typename _Tp1,typename _Tp2>
		constexpr bool chkmin(_Tp1 &x,_Tp2 y){
			return y<x?(x=y,true):false;
		}
		template<typename _Tp1,typename _Tp2,typename...Args>
		constexpr bool chkmin(_Tp1 &x,_Tp2 y,Args ...args){
			return chkmin(x,y)|chkmin(x,args...);
		}
		template<typename _Tp1,typename _Tp2>
		constexpr bool chkmax(_Tp1 &x,_Tp2 y){
			return x<y?(x=y,true):false;
		}
		template<typename _Tp1,typename _Tp2,typename...Args>
		constexpr bool chkmax(_Tp1 &x,_Tp2 y,Args ...args){
			return chkmax(x,y)|chkmax(x,args...);
		}
		template<typename _Tp,
		typename std::enable_if<!Traits_Tools::has_member_swap<_Tp>::value&&!std::is_integral<_Tp>::value>::type* =nullptr>
		constexpr void swap(_Tp &x,_Tp &y){
			_Tp tmp;
			tmp=x,x=y,y=tmp;
		}
		template<typename _Tp,typename std::enable_if<std::is_integral<_Tp>::value>::type* =nullptr>
		constexpr void swap(_Tp &x,_Tp &y){
			x!=y&&(x^=y^=x^=y);
		}
		template<typename _Tp>
		constexpr void swap(_Tp *&x,_Tp *&y){
			_Tp *tmp;
			tmp=x,x=y,y=tmp;
		}
		template<typename _Tp,typename std::enable_if<Traits_Tools::has_member_swap<_Tp>::value>::type* =nullptr>
		constexpr void swap(_Tp &x,_Tp &y){
			x.swap(y);
		}
		template<typename _Tp>
		constexpr _Tp abs(const _Tp &x){
			return x<0?-x:x;
		}
	}
}
namespace QL{
	/**
	 * gcd is 1 for floating
	*/
	namespace Math_Tools{
		namespace Math_Tools_base{
			template<typename _Tp,typename _Used>
			constexpr _Tp qpow(ull x,_Used p,_Tp mod){
				_Tp ret=1;
				for(;p;p>>=1,x=x*x%mod) if(p&1) ret=ret*x%mod;
				return ret;
			}
		}
		template<typename _Tp,typename _Used>
		constexpr _Tp qpow(_Tp x,_Used p,_Tp mod){
			if(unlikely(x<0)) x=mod+(x%mod);
			return Math_Tools_base::qpow(x,p,mod);
		}
		template<typename _Tp,typename _Used>
		constexpr _Tp qpow(_Tp x,_Used p){
			_Tp ret=1;
			for(;p;p>>=1,x=x*x) if(p&1) ret=ret*x;
			return ret;
		}
		template<typename _Tp>
		constexpr _Tp inv(_Tp x,_Tp mod){
			return Math_Tools_base::qpow(x,mod-2,mod);
		}
		template<typename _Tp>
		constexpr auto gcd(_Tp a,_Tp b,typename std::enable_if<std::is_integral<_Tp>::value>::type* =nullptr){
			return b?gcd(b,a%b):a;
		}
		template<typename _Tp>
		constexpr auto gcd(_Tp a,_Tp b,typename std::enable_if<std::is_floating_point<_Tp>::value>::type* =nullptr){
			return 1;
		}
		template<typename _Tp>
		constexpr auto lcm(_Tp a,_Tp b){
			return a/gcd(a,b)*b;
		}
	}
}
#if __cplusplus<201703L
namespace QL{
	namespace Array{
		template<typename _Tp,unsigned N>
		class array{
		private:
			_Tp arr[N];
		public:
			constexpr unsigned size()const{return N;}
			constexpr _Tp &operator[](unsigned _n){
				return arr[_n];
			}
			constexpr _Tp operator[](unsigned _n)const{
				return arr[_n];
			}
		};
	}
}
#endif
namespace QL{
	/**
	 * 多项式,占坑
	 * 以后会尽量补全的
	 */
	namespace Poly_Tools{
		namespace Poly_Base{
			constexpr uint max_g=22,max_len=2<<20;
			constexpr uint pw[]{0,1,2,4,8,16,32,64,128,256,512,1024};
			uint rev[max_len];
			constexpr void ReInit(uint n){
				for(uint i(0);i<n;++i) rev[i]=(rev[i>>1]>>1)|((i&1)?(n>>1):0);
			}
			constexpr uint to_up(uint x){
				#define cs(x) case pw[x] ... pw[x+1]-1: return pw[x+1];
				switch(x){
					cs(0)cs(1)cs(2)cs(3)cs(4)cs(5)cs(6)cs(7)cs(8)cs(9)cs(10)
					default: return 1u<<(32-__builtin_clz(x));
				}
				#undef cs
			}
		}
		namespace ComplexNumber{
			template<typename _Tp>
			struct complex{
				_Tp real,imag;
				constexpr complex():real{},imag{}{}
				template<typename T>
				constexpr complex(const T &_real):real(_real),imag{}{}
				template<typename T1,typename T2>
				constexpr complex(const T1 &_real,const T2 &_imag):real(_real),imag(_imag){}
				template<typename T>
				constexpr complex(const complex<T> &it):real(it.real),imag(it.imag){}
				constexpr complex operator+(const complex &it)const{
					return complex(real+it.real,imag+it.imag);
				}
				constexpr complex operator-(const complex &it)const{
					return complex(real-it.real,imag-it.imag);
				}
				constexpr complex operator*(const complex &it)const{
					return complex(real*it.real-imag*it.imag,imag*it.real+real*it.imag);
				}
			};
		}
		namespace Primitive_Root{
#if __cplusplus<201703L
			template<typename _Tp,unsigned N>
			using array=QL::Array::array<_Tp,N>;
#else
			template<typename _Tp,unsigned N>
			using array=std::array<_Tp,N>;
#endif
			template<typename _U_Tp>
			static constexpr auto init_for_gn(_U_Tp p,_U_Tp g){
				array<_U_Tp,Poly_Base::max_g> ret{};
				for(uint i(0);i<Poly_Base::max_g;++i) ret[i]=Math_Tools::qpow(g,(p-1)>>i,p);
				return ret;
			}
			template<typename _U_Tp>
			static constexpr auto init_for_inv(_U_Tp p,_U_Tp g){
				array<_U_Tp,Poly_Base::max_g> ret{};
				_U_Tp v=Math_Tools::inv(g,p);
				for(uint i(0);i<Poly_Base::max_g;++i) ret[i]=Math_Tools::qpow(v,(p-1)>>i,p);
				return ret;
			}
			struct Prim_Root{};
			/**
			 * todo:
			 * find the prim root
			 * support more types
			*/
			struct runtime_Prim_Root:Prim_Root{
				uint p,g;
				array<uint,Poly_Base::max_g> gn,inv;
				runtime_Prim_Root():p{},g{},gn{},inv{}{}
				runtime_Prim_Root(uint _p,uint _g):p{_p},g{_g},gn{init_for_gn(p,g)},inv{init_for_inv(g,p)}{}
			};
			template<typename _U_Tp,_U_Tp _p,_U_Tp _g>
			struct const_Prim_Root:Prim_Root{
				static constexpr _U_Tp p{_p},g{_g};
				static constexpr array<_U_Tp,Poly_Base::max_g> gn{init_for_gn(_p,_g)},inv{init_for_inv(_p,_g)};
			};
			template<typename _U_Tp,_U_Tp _p,_U_Tp _g>
			constexpr _U_Tp const_Prim_Root<_U_Tp,_p,_g>::p;
			template<typename _U_Tp,_U_Tp _p,_U_Tp _g>
			constexpr _U_Tp const_Prim_Root<_U_Tp,_p,_g>::g;
			template<typename _U_Tp,_U_Tp _p,_U_Tp _g>
			constexpr array<_U_Tp,Poly_Base::max_g> const_Prim_Root<_U_Tp,_p,_g>::gn;
			template<typename _U_Tp,_U_Tp _p,_U_Tp _g>
			constexpr array<_U_Tp,Poly_Base::max_g> const_Prim_Root<_U_Tp,_p,_g>::inv;
			using G_998244353i=const_Prim_Root<uint,998244353,3>;
			using G_1004535809i=const_Prim_Root<uint,1004535809,3>;
			using G_46976204i=const_Prim_Root<uint,469762049,3>;
		}
		/**
		 * 暴力乘法(划掉)
		 * upd:FFT
		 */
		using Base_Tools::swap;
		using namespace rel_ops::Calc_Self;
		namespace Poly_Base{
			template<typename _Tp>
			class Poly{
			protected:
				_Tp *p;
				uint n;
			public:
				constexpr uint length(void)const{return n;}
				constexpr Poly():p{},n{}{}
				constexpr Poly(const uint &_n):p{new _Tp[_n]{}},n{_n}{}
				constexpr Poly(const std::initializer_list<_Tp> &L){
					delete[] p;
					p=new _Tp[L.size()]{},n=0;
					for(auto it:L) p[n++]=it;
				}
				constexpr Poly(const Poly &it):n{it.n}{
					p=new _Tp[it.n]{},n=it.n;
					memcpy(p,it.p,sizeof(_Tp)*it.n);
				}
				constexpr void resize(const uint &_n){
					delete[] p;
					p=new _Tp[_n]{},n=_n;
				}
				constexpr Poly &operator=(const Poly &it){
					if(this==&it) return *this;
					delete[] p;
					p=new _Tp[it.n]{},n=it.n;
					memcpy(p,it.p,sizeof(_Tp)*it.n);
					return *this;
				}
				constexpr _Tp &operator[](const uint &x){
					if(x>=n) Error::make_re();
					return p[x];
				}
				constexpr const _Tp &operator[](const uint &x)const{
					if(x>=n) Error::make_re();
					return p[x];
				}
				~Poly(){
					delete[] p;
				}
			};
		}
		namespace Transforms{
			namespace For_FFT{
				using Complex=ComplexNumber::complex<db>;
				Complex f[Poly_Base::max_len];
				constexpr db PI=acos(-1);
				constexpr void FFT_transform(Complex *f,uint n,int type){
					for(uint i(0);i<n;++i) if(i<Poly_Base::rev[i]) swap(f[i],f[Poly_Base::rev[i]]);
					for(uint p(1),l(2);l<=n;p=l,l<<=1){
						Complex step(cos(PI/p),type*sin(PI/p));
						for(uint i(0);i<n;i+=l){
							Complex *g=f+i,*h=g+p,w(1,0),t;
							for(uint k(0);k<p;++k,w=w*step)
								t=h[k]*w,h[k]=g[k]-t,g[k]=g[k]+t;
						}
					}
				}
			}
		}
		template<typename _Tp>
		class FFT:public Poly_Base::Poly<_Tp>{
			using Poly=Poly_Base::Poly<_Tp>;
		public:
			constexpr FFT():Poly(){}
			constexpr FFT(const Poly &poly):Poly(poly){}
			constexpr Poly operator*(const FFT<_Tp> &it){
				using namespace Transforms::For_FFT;
				Poly ret(Poly::n+it.length()-1);
				uint x(Poly_Base::to_up(ret.length()));
				for(uint i(0);i<x;++i) f[i]=Complex(0,0);
				for(uint i(0);i<Poly::n;++i) f[i].real=Poly::p[i];
				for(uint i(0);i<it.length();++i) f[i].imag=it[i];
				Poly_Base::ReInit(x);
				FFT_transform(f,x,1);
				for(uint i(0);i<x;++i) f[i]*=f[i];
				FFT_transform(f,x,-1);
				for(uint i(0);i<ret.length();++i) ret[i]=f[i].imag/x/2.0+0.5;
				return ret;
			}
		};
		namespace Transforms{
			namespace For_NTT{
				template<bool type,typename _Prim_Root>
				constexpr void NTT_transform(ull *f,uint n,const _Prim_Root &pr){
					static_assert(std::is_base_of<Primitive_Root::Prim_Root,_Prim_Root>::value,
					"In NTT(transform): Prim_Root is invalid,Please use the class in QL::Primitive_Root.");
					for(uint i(0);i<n;++i) if(i<Poly_Base::rev[i]) swap(f[i],f[Poly_Base::rev[i]]);
					for(uint p(1),l(2),d(1);l<=n;p=l,l<<=1,++d){
						ull step(type?pr.gn[d]:pr.inv[d]);
						for(uint i(0);i<n;i+=l){
							ull *g=f+i,*h=g+p,w(1),t;
							for(uint k(0);k<p;++k,w=w*step%pr.p)
								t=h[k]*w%pr.p,h[k]=(g[k]+pr.p-t)%pr.p,g[k]=(g[k]+t)%pr.p;
						}
					}
				}
				ull f[Poly_Base::max_len],g[Poly_Base::max_len];
			}
		};
		template<typename _Tp,typename _Prim_Root=Primitive_Root::G_998244353i>
		class NTT:public Poly_Base::Poly<_Tp>{
			using Poly=Poly_Base::Poly<_Tp>;
			static _Prim_Root pr;
			static_assert(std::is_integral<_Tp>::value,
			"In NTT(class): The type is not an integral.");
			static_assert(std::is_base_of<Primitive_Root::Prim_Root,_Prim_Root>::value,
			"In NTT(class): Prim_Root is invalid,Please use the class in QL::Primitive_Root.");
		public:
			constexpr NTT():Poly(){}
			constexpr NTT(const Poly &poly):Poly(poly){}
			constexpr Poly operator*(const NTT<_Tp,_Prim_Root> &it){
				using namespace Transforms::For_NTT;
				Poly ret(Poly::n+it.length()-1);
				uint x(Poly_Base::to_up(ret.length()));
				for(uint i(0);i<Poly::n;++i) f[i]=Poly::p[i];
				for(uint i(Poly::n);i<x;++i) f[i]=0;
				for(uint i(0);i<it.length();++i) g[i]=it[i];
				for(uint i(it.length());i<x;++i) g[i]=0;
				Poly_Base::ReInit(x);
				NTT_transform<true>(f,x,pr);
				NTT_transform<true>(g,x,pr);
				for(uint i(0);i<x;++i) f[i]=f[i]*g[i]%pr.p;
				NTT_transform<false>(f,x,pr);
				for(uint i(0);i<ret.length();++i) ret[i]=f[i]*Math_Tools::qpow(x,pr.p-2,pr.p)%pr.p;
				return ret;
			}
		};
		template<typename _Tp,typename _Prim_Root>
		_Prim_Root NTT<_Tp,_Prim_Root>::pr;
	}
}
namespace MAIN{
	/* 主函数在这捏…… */
	using namespace QL;
	using QL::IO::lq;
	using QL::Poly_Tools::NTT;
	int n,m;
	NTT<int> f,g;
	signed _main_(){
		lq.read(n,m);
		f.resize(n+1);
		g.resize(m+1);
		for(int i=0;i<=n;++i) lq.read(f[i]);
		for(int i=0;i<=m;++i) lq.read(g[i]);
		f=f*g;
		for(uint i(0);i<f.length();++i) lq.write(f[i],' ');
		return 0;
	}
}
signed main(){
	return MAIN::_main_();
}

参考

command-block 的 Poly 全家桶

知乎上的一篇

OI-wiki 上的原根

posted @   LQ636721  阅读(32)  评论(2编辑  收藏  举报
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