FFT板子

Posted 2020-12-15 hn-wrp

#include <cmath>
#include <cstdio>
#include <vector>
#include <cstring>
#include <algorithm>

using namespace std;

#define R register
#define LL long long
const int inf=0x3f3f3f3f;
const int MAXN=4e6+10;
const double PI=3.1415926535897932384626;

inline int read() {
	char a=getchar(); int x=0,f=1;
	for(;a>‘9‘||a<‘0‘;a=getchar()) if(a==‘-‘) f=-1;
	for(;a>=‘0‘&&a<=‘9‘;a=getchar()) x=x*10+a-‘0‘;
	return x*f;
}

namespace Data {
	struct Complex {
		double x, y;
		Complex (double X = 0, double Y = 0) { x = X; y = Y; }
	};
	inline Complex operator + (Complex a, Complex b) { return Complex( a.x+b.x, a.y+b.y ); }
	inline Complex operator - (Complex a, Complex b) { return Complex( a.x-b.x, a.y-b.y ); }
	inline Complex operator * (Complex a, Complex b) { return Complex( a.x*b.x-a.y*b.y, a.x*b.y+a.y*b.x ); }
}

namespace Operation {
	using Data::Complex;
	int lim,bit;
	int rev[MAXN];
	inline void FFT ( Complex *A, int type ) {
		for(R int i=0; i<lim; i++) if( i < rev[i] ) swap( A[i] , A[rev[i]] );
		for(R int dep=1; dep < lim; dep<<=1) {
			Complex Wn( cos(PI/dep), type*sin(PI/dep) );
			for(R int len=dep<<1,j=0 ;j<lim ;j+=len) {
				Complex w(1,0);
				for(R int k=0 ;k<dep ;k++,w=w*Wn) {
					Complex x=A[j+k],y=w*A[j+dep+k];
					A[j+k]=x+y;
					A[j+dep+k]=x-y;
				}
			}
		}
		if(type==-1) 
			for(R int i=0;i<=lim;i++) A[i].x/=lim;
	} 
	inline void Turn(Complex *A,Complex *B,int n,int m) {
		lim=1; bit=0;
		while( lim <= n+m ) lim<<=1,bit++;
		for(R int i=0; i<lim; i++) rev[i] = (rev[i>>1]>>1)|((i&1)<<(bit-1)); 
		FFT(A,1); FFT(B,1);
		for(R int i=0; i<=lim; i++) A[i] = A[i] * B[i];
		FFT(A,-1);
	}
}

using namespace Data;

int n,m;
Complex f[MAXN],g[MAXN];

int main() {
	//freopen(".in","r",stdin);
	//freopen(".out","w",stdout);
	n=read(); m=read();
	for(R int i=0;i<=n;i++) f[i].x=read();
	for(R int i=0;i<=m;i++) g[i].x=read();
	Operation::Turn(f,g,n,m);
	for(R int i=0;i<=n+m;i++) printf("%d ",(int)(f[i].x+0.5));
	return 0;	
}