hdu5829

多校训练8，有官方题解

主要之前没写过ntt，感觉不是很懂原根

先贴一份当模板吧

 #include<iostream>
 #include<cstdio>
 #include<cmath>
 #include<cstring>
 #include<algorithm>
 typedef long long ll;
 using namespace std;
 const int mo=;
 const int g=;
 int e[],a[*],b[*],jc[],d[],ni[],r[*];
 int w[][],ans[],rg[];
 int cas,m,n;
 bool cmp(int a,int b)
 {
   return a>b;
 }

 ll quick(ll x,int y)
 {
   ll s=;
   while (y)
   {
     if (y&) s=s*x%mo;
     x=x*x%mo; y>>=;
   }
   return s;
 }
 void ntt(int *a, int f)
 {
   for (int i=; i<n; i++)
     if (i<r[i]) swap(a[i],a[r[i]]);
   int now=;
   for (int i=; i<n; i<<=)
   {
     int p=w[++now][f];
     for (int j=; j<n; j+=i<<)
     {
       int w=;
       for (int k=; k<i; k++)
       {
          int u=a[k+j],v=1ll*w*a[j+k+i]%mo;
          a[j+k]=(u+v)%mo;
          a[j+k+i]=(u-v+mo)%mo;
          w=1ll*w*p%mo;
       }
     }
   }
 }

 int main()
 {
   freopen("1.in","r",stdin);
   int now=(mo-)/,ng=quick(g,mo-),l=;
   while (now%==)
   {
     w[++l][]=quick(g,now);
     w[l][]=quick(ng,now);
     rg[l]=quick(<<l,mo-);
     now>>=;
   }
   jc[]=d[]=ni[]=;
   for (int i=; i<=; i++)
   {
     jc[i]=1ll*jc[i-]*i%mo;
     ni[i]=quick(jc[i],mo-);
     d[i]=*d[i-]%mo;
   }
   scanf("%d",&cas);
   while (cas--)
   {
     scanf("%d",&m);
     for (int i=; i<=m; i++)
       scanf("%d",&e[i]);
     sort(e+,e++m,cmp);
     memset(a,,sizeof(a));
     memset(b,,sizeof(b));
     for (int i=; i<=m; i++)
       a[i]=1ll*jc[i-]*d[m-i]%mo*e[i]%mo;
     for (int i=; i<=m; i++)
       b[m-i]=ni[i];
    /* for (int i=m+1; i<2*m+1; i++)
     {
       int s=0;
       for (int j=0; j<=i; j++) s=(s+1ll*a[j]*b[i-j]%mo)%mo;
       cout <<1ll*s*ni[i-m-1]%mo<<" ";
     }
     cout <<endl;
     break;*/
     int l=;
     for (n=; n<=*m+; n<<=) l++;
     for (int i=; i<n; i++) r[i]=(r[i>>]>>)|((i&)<<(l-));
     ntt(a,); ntt(b,);
     for (int i=; i<n; i++) a[i]=1ll*a[i]*b[i]%mo;
     ntt(a,);
     for (int i=m+; i<*m+; i++)
       ans[i-m]=1ll*a[i]*ni[i-m-]%mo*rg[l]%mo;
     for (int i=; i<=m; i++)
       ans[i]=(ans[i-]+ans[i])%mo;
     for (int i=; i<=m; i++)
       printf("%d ",ans[i]);
     cout <<endl;
   }
   return ;
 }