【数学】多项式取 ln
多项式取 ln
模板题传送门
给你 \(A\),让你求 \(B(x) \equiv lnA(x) \pmod {x^n}\)
两遍求导,得到 \(B'(x) \equiv \frac{A'(x)}{A(x)} \pmod {x^n}\)
然后积分即有 \(B(x) \equiv \int\frac{A'(x)}{A(x)}dx \pmod {x^n}\)
#include
using namespace std;
#define debug(x) cerr << #x << ": " << (x) << endl
#define rep(i,a,b) for(int i=(a);i<=(b);i++)
#define dwn(i,a,b) for(int i=(a);i>=(b);i--)
using pii = pair;
using ll = long long;
#define int long long
inline void read(int &x){
int s=0; x=1;
char ch=getchar();
while(ch<'0' || ch>'9') {if(ch=='-')x=-1;ch=getchar();}
while(ch>='0' && ch<='9') s=(s<<3)+(s<<1)+ch-'0',ch=getchar();
x*=s;
}
const int N=3e5+5, rt=3, mod=998244353;
int rev[N], tot=1, bit;
ll fpow(ll x, int p, ll mod){
int res=1;
for(; p; p>>=1, x=x*x%mod) if(p&1) res=res*x%mod;
return res;
}
ll inv(ll x, ll mod){
return fpow(x, mod-2, mod);
}
ll mul(ll x, int p, ll mod){
ll res=0;
for(; p; p>>=1, x=(x+x)%mod) if(p&1) res=(res+x)%mod;
return res;
}
void NTT(ll *a, int type, int mod){
for(int i=0; i>1, a, b);
// init
bit=0, tot=1;
while(tot<=(sz-1<<1)) tot<<=1, bit++;
for(int i=0; i>1]>>1)|((i&1)<<(bit-1));
rep(i,0,sz-1) C[i]=a[i];
rep(i,sz,tot-1) C[i]=0;
NTT(C, 1, mod), NTT(b, 1, mod);
rep(i,0,tot-1) b[i]=(2-C[i]*b[i]%mod+mod)%mod*b[i]%mod;
NTT(b, -1, mod);
rep(i,sz,tot-1) b[i]=0;
}
void poly_der(int sz, int *a, int *b){
rep(i,1,sz-1) b[i-1]=i*a[i]%mod;
b[sz-1]=0;
}
void poly_int(int sz, int *a, int *b){
rep(i,1,sz-1) b[i]=a[i-1]*inv(i, mod)%mod;
b[0]=0;
}
int inv_A[N], der_A[N];
void conv(int *a, int *b){
NTT(a, 1, mod), NTT(b, 1, mod);
rep(i,0,tot-1) a[i]=a[i]*b[i]%mod;
NTT(a, -1, mod);
}
void poly_ln(int sz, int *a, int *b){
poly_inv(sz, a, inv_A);
poly_der(sz, a, der_A);
// init
bit=0, tot=1;
while(tot<=sz-1+sz-2) tot<<=1, bit++;
for(int i=0; i>1]>>1)|((i&1)<<(bit-1));
conv(inv_A, der_A);
poly_int(sz, inv_A, b);
}
signed main(){
cin>>n;
rep(i,0,n-1) read(A[i]);
poly_ln(n, A, B);
rep(i,0,n-1) cout<