洛谷.3803.[模板]多项式乘法(NTT)

题目链接：洛谷、LOJ.

为什么和那些差那么多啊。。

#include <cstdio>
#include <cctype>
#include <algorithm>
#define P (998244353)
#define G (3)
#define inv_G (332748118)
//#define gc() getchar()
#define MAXIN 300000
#define gc() (SS==TT&&(TT=(SS=IN)+fread(IN,1,MAXIN,stdin),SS==TT)?EOF:*SS++)
typedef long long LL;
const int N=(1<<21)+5;//2 097 152 //2e6+5;

int n,m,rev[N];
LL A[N],B[N],inv_lim;//全换成int好像大概略快吧 
char IN[MAXIN],*SS=IN,*TT=IN;

inline int read()
{
    register char c=gc();
    for(;!isdigit(c);c=gc());
    return c-'0';//233
}
inline LL FP(LL x,LL k)
{
    LL t=1;
    for(; k; k>>=1,x=x*x%P)
        if(k&1) t=t*x%P;
    return t;
}
void NTT(LL *a,int lim,int type)
{
    for(int i=0; i<lim; ++i)
        if(i<rev[i]) std::swap(a[i],a[rev[i]]);
    for(int i=2; i<=lim; i<<=1)
    {
        int mid=i>>1;
        LL Wn=FP(~type?G:inv_G,(P-1)/i),t,w;
        for(int j=0; j<lim; j+=i)
        {
            LL w=1;
            for(int k=0; k<mid; ++k, w=w*Wn%P)
                a[j+k+mid]=(a[j+k]-(t=w*a[j+k+mid]%P)+P)%P,
                a[j+k]=(a[j+k]+t)%P;
        }
    }
    if(type==-1) for(int i=0; i<lim; ++i) a[i]=a[i]*inv_lim%P;
}

int main()
{
    scanf("%d%d",&n,&m);//sb了拿那个read读n,m。。
    for(int i=0; i<=n; ++i) A[i]=read();//(read()%P+P)%P
    for(int i=0; i<=m; ++i) B[i]=read();
    int lim=1,len=0;
    while(lim<=n+m) lim<<=1,++len;
    inv_lim=FP(lim,P-2);
    for(int i=1; i<lim; ++i)
        rev[i] = (rev[i>>1]>>1) | ((i&1)<<len-1);
    NTT(A,lim,1), NTT(B,lim,1);
    for(int i=0; i<lim; ++i) A[i]=A[i]*B[i]%P;
    NTT(A,lim,-1);
    for(int i=0; i<=n+m; ++i) printf("%lld ",A[i]);

    return 0;
}