Luogu5205 模板多项式开根(NTT+多项式求逆)
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https://www.cnblogs.com/HocRiser/p/8207295.html 安利!
写NTT把i<<=1写成了i<<=2,又调了一年。发现我的日常就是数组开小调调调,变量名写错调调调,反向判if调调调,退役吧。
#include<iostream> #include<cstdio> #include<cmath> #include<cstdlib> #include<cstring> #include<algorithm> using namespace std; #define ll long long #define P 998244353 #define N 550000 char getc(){char c=getchar();while ((c<‘A‘||c>‘Z‘)&&(c<‘a‘||c>‘z‘)&&(c<‘0‘||c>‘9‘)) c=getchar();return c;} int gcd(int n,int m){return m==0?n:gcd(m,n%m);} int read() { int x=0,f=1;char c=getchar(); while (c<‘0‘||c>‘9‘) {if (c==‘-‘) f=-1;c=getchar();} while (c>=‘0‘&&c<=‘9‘) x=(x<<1)+(x<<3)+(c^48),c=getchar(); return x*f; } int n,a[N],r[N],b[N],A[N],B[N],f[N],g[N],t; int ksm(int a,int k) { int s=1; for (;k;k>>=1,a=1ll*a*a%P) if (k&1) s=1ll*s*a%P; return s; } int inv(int a){return ksm(a,P-2);} void DFT(int n,int *a,int g) { for (int i=0;i<n;i++) r[i]=(r[i>>1]>>1)|(i&1)*(n>>1); for (int i=0;i<n;i++) if (i<r[i]) swap(a[i],a[r[i]]); for (int i=2;i<=n;i<<=1) { int wn=ksm(g,(P-1)/i); for (int j=0;j<n;j+=i) { int w=1; for (int k=j;k<j+(i>>1);k++,w=1ll*w*wn%P) { int x=a[k],y=1ll*w*a[k+(i>>1)]%P; a[k]=(x+y)%P,a[k+(i>>1)]=(x-y+P)%P; } } } } void IDFT(int *a,int n) { DFT(n,a,inv(3)); int u=inv(n); for (int i=0;i<n;i++) a[i]=1ll*a[i]*u%P; } void mul(int *a,int *b,int n) { DFT(n,a,3),DFT(n,b,3); for (int i=0;i<n;i++) a[i]=1ll*a[i]*b[i]%P; IDFT(a,n); } void Inv(int *a,int *b,int n) { if (n==1) {for (int i=0;i<t;i++) b[i]=0;b[0]=inv(a[0]);return;} Inv(a,b,n>>1); for (int i=0;i<n;i++) A[i]=a[i]; for (int i=n;i<(n<<1);i++) A[i]=0; n<<=1; DFT(n,A,3),DFT(n,b,3); for (int i=0;i<n;i++) b[i]=1ll*b[i]*(P+2-1ll*A[i]*b[i]%P)%P; IDFT(b,n); n>>=1; for (int i=n;i<(n<<1);i++) b[i]=0; } void Sqrt(int *a,int *b,int n) { if (n==1) {for (int i=0;i<t;i++) b[i]=0;b[0]=1;return;} Sqrt(a,b,n>>1);Inv(b,B,n); for (int i=0;i<n;i++) A[i]=a[i]; for (int i=n;i<(n<<1);i++) A[i]=0; n<<=1; DFT(n,A,3),DFT(n,b,3),DFT(n,B,3); int inv2=inv(2); for (int i=0;i<n;i++) b[i]=(b[i]+1ll*A[i]*B[i]%P)*inv2%P; IDFT(b,n); n>>=1; for (int i=n;i<(n<<1);i++) b[i]=0; } int main() { #ifndef ONLINE_JUDGE freopen("sqrt.in","r",stdin); freopen("sqrt.out","w",stdout); const char LL[]="%I64d "; #else const char LL[]="%lld "; #endif n=read(); for (int i=0;i<n;i++) a[i]=read(); t=1;while (t<=n) t<<=1; Sqrt(a,b,t); for (int i=0;i<n;i++) printf("%d ",b[i]); return 0; }
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