FFT

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<algorithm>
 4 #include<vector>
 5 #include<cstdlib>
 6 #include<cmath>
 7 #include<cstring>
 8 #include<complex>
 9 using namespace std;
10 #define maxn 1001000
11 #define llg long long 
12 #define Pi acos(-1.0)
13 #define yyj(a) freopen(a".in","r",stdin),freopen(a".out","w",stdout);
14 typedef complex<double> XU;
15 
16 struct FFT
17 {
18     llg rev[maxn],L,n,m,c[maxn];
19     
20     void fft(XU *z,llg f)
21     {
22         for (llg i=0;i<n;i++) if (i<rev[i]) swap(z[i],z[rev[i]]);
23         for (llg i=1;i<n;i*=2)
24         {
25             XU wn(cos(Pi/i),sin(Pi/i));
26             for (llg p=i*2,j=0;j<n;j+=p)
27             {
28                 XU w(1,0);
29                 for (llg k=0;k<i;k++,w*=wn)
30                 {
31                     XU x=z[j+k],y=w*z[j+k+i];
32                     z[j+k]=x+y,z[j+k+i]=x-y;
33                 }
34             }
35         }
36         if (f==-1) reverse(z+1,z+n);
37     }
38 
39     XU a[maxn],b[maxn];
40 
41     void work()
42     {
43         m+=n;
44         for (n=1;n<=m;n*=2) L++;
45         for (llg i=0;i<n;i++) rev[i]=(rev[i/2]/2)|((i&1)<<(L-1));
46         fft(a,1); fft(b,1);
47         for (llg i=0;i<n;i++) a[i]=a[i]*b[i];
48         fft(a,-1);
49         for (llg i=0;i<=m;i++) c[i]=(llg)(a[i].real()/n+0.5);
50     }
51 
52 }fft;
53 
54 llg read() {llg x; scanf("%lld",&x); return x;}
55 
56 int main()
57 {
58     yyj("fft");
59     cin>>fft.n>>fft.m;
60     for (llg i=0;i<=fft.n;i++) fft.a[i]=read();
61     for (llg i=0;i<=fft.m;i++) fft.b[i]=read();
62     fft.work();
63     for (llg i=0;i<=fft.m;i++) printf("%lld ",fft.c[i]);
64     return 0;
65 }