1 #include <cmath>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cstdlib>
 5 #include <iostream>
 6 #include <algorithm>
 7 
 8 const int MAXN=270000;
 9 const int DFT=1;
10 const int IDFT=-1;
11 const double PI=acos(-1);
12 
13 struct Complex{
14     double real;
15     double imag;
16     Complex(double r=0,double i=0){
17         this->real=r;
18         this->imag=i;
19     }
20 };
21 Complex operator+(Complex a,Complex b){
22     return Complex(a.real+b.real,a.imag+b.imag);
23 }
24 Complex operator-(Complex a,Complex b){
25     return Complex(a.real-b.real,a.imag-b.imag);
26 }
27 Complex operator*(Complex a,Complex b){
28     return Complex(a.real*b.real-a.imag*b.imag,a.real*b.imag+a.imag*b.real);
29 }
30 
31 Complex a[MAXN],b[MAXN],c[MAXN];
32 
33 int n;             //Length of a
34 int m;             //Length of b
35 int bln=1;         //Binary Length
36 int bct;           //Bit Count
37 int len;           //Length Sum
38 int rev[MAXN];     //Binary Reverse Sort
39 
40 void Initialize();
41 void FFT(Complex*,int,int);
42 
43 int main(){
44     Initialize();
45     FFT(a,bln,DFT);
46     FFT(b,bln,DFT);
47     for(int i=0;i<=bln;i++){
48         c[i]=a[i]*b[i];
49     }
50     FFT(c,bln,IDFT);
51     for(int i=0;i<=len;i++){
52         printf("%d ",int(c[i].real/bln+0.5));
53     }
54     putchar(‘\n‘);
55     return 0;
56 }
57 
58 void FFT(Complex* a,int len,int opt){
59     for(int i=0;i<len;i++)
60         if(i<rev[i])
61             std::swap(a[i],a[rev[i]]);
62     for(int i=1;i<len;i<<=1){
63         Complex wn=Complex(cos(PI/i),opt*sin(PI/i));
64         int step=i<<1;
65         for(int j=0;j<len;j+=step){
66             Complex w=Complex(1,0);
67             for(int k=0;k<i;k++,w=w*wn){
68                 Complex x=a[j+k];
69                 Complex y=w*a[j+k+i];
70                 a[j+k]=x+y;
71                 a[j+k+i]=x-y;
72             }
73         }
74     }
75 }
76 
77 void Initialize(){
78     scanf("%d%d",&n,&m);
79     len=n+m;
80     while(bln<=len){
81         bct++;
82         bln<<=1;
83     }
84     for(int i=0;i<bln;i++){
85         rev[i]=(rev[i>>1]>>1)|((i&1)<<(bct-1));
86     }
87     for(int i=0;i<=n;i++){
88         scanf("%lf",&a[i].real);
89     }
90     for(int i=0;i<=m;i++){
91         scanf("%lf",&b[i].real);
92     }
93 }