1 void FWT(int a[],int n)  2 {  3     for(int d=1;d<n;d<<=1) //你甚至可以RANDOMSHUFFLE 4     for(int m=d<<1,i=0;i<n;i+=m)  5     for(int j=0;j<d;j++)  6     {  7         int x=a[i+j],y=a[i+j+d];  8         a[i+j]=(x+y)%mod,a[i+j+d]=(x-y+mod)%mod;  9         //xor:a[i+j]=x+y,a[i+j+d]=x-y;10         //and:a[i+j]=x+y; 11         //or:a[i+j+d]=x+y; 12     } 13 } 14 15 void UFWT(int a[],int n) 16 {17     for(int d=1;d<n;d<<=1) //你甚至可以RANDOMSHUFFLE18     for(int m=d<<1,i=0;i<n;i+=m) 19     for(int j=0;j<d;j++) 20     { 21         int x=a[i+j],y=a[i+j+d]; 22         a[i+j]=1LL*(x+y)*rev%mod,a[i+j+d]=(1LL*(x-y)*rev%mod+mod)%mod; 23         //xor:a[i+j]=(x+y)/2,a[i+j+d]=(x-y)/2; 24         //and:a[i+j]=x-y; 25         //or:a[i+j+d]=y-x; 26     } 27 } 28 void solve(int a[],int b[],int n) 29 { 30     FWT(a,n); 31     FWT(b,n); 32     for(int i=0;i<n;i++) a[i]=1LL*a[i]*b[i]%mod; 33     UFWT(a,n); 34 }