多项式取模优化k阶常系数线性递推的模板
刚才的板子改了一下，wa了，，，先码这吧，下次再改。
1 //Achen 2 #include<algorithm> 3 #include<iostream> 4 #include<cstring> 5 #include<cstdlib> 6 #include<vector> 7 #include<cstdio> 8 #include<queue> 9 #include<cmath> 10 #include<set> 11 #include<map> 12 #define Formylove return 0 13 #define For(i,a,b) for(int i=(a);i<=(b);i++) 14 #define Rep(i,a,b) for(int i=(a);i>=(b);i--) 15 const int N=4007,p=1000000007; 16 typedef long long LL; 17 typedef double db; 18 using namespace std; 19 LL a[N],f[N],n,k; 20 21 template<typename T>void read(T &x) { 22 char ch=getchar(); x=0; T f=1; 23 while(ch!='-'&&(ch<'0'||ch>'9')) ch=getchar(); 24 if(ch=='-') f=-1,ch=getchar(); 25 for(;ch>='0'&&ch<='9';ch=getchar()) x=x*10+ch-'0'; x*=f; 26 } 27 28 LL rs[N],bs[N]; 29 void mul(LL a[],LL b[],LL c[]) { 30 static LL tp[N]; 31 int up=(k<<1); 32 For(i,0,up) tp[i]=0; 33 For(i,0,k-1) For(j,0,k-1) 34 (tp[i+j]+=a[i]*b[j]%p)%=p; 35 Rep(i,up,k) { 36 For(j,1,k) (tp[i-j]+=f[j]*tp[i]%p)%=p; 37 tp[i]=0; 38 } 39 For(i,0,up) c[i]=tp[i]; 40 } 41 42 void ksm(LL b) { 43 while(b) { 44 if(b&1) mul(rs,bs,rs); 45 mul(bs,bs,bs); 46 b>>=1; 47 } 48 } 49 50 //#define ANS 51 int main() { 52 #ifdef ANS 53 freopen("shanghai.in","r",stdin); 54 freopen("shanghai.out","w",stdout); 55 #endif 56 read(n); read(k); 57 For(i,1,k) read(f[i]); 58 For(i,1,k) { read(a[i]); (a[i]+=p)%=p; } 59 if(n<k) { 60 printf("%lld ",a[n+1]); 61 return 0; 62 } 63 rs[0]=1; bs[1]=1; 64 ksm(n); 65 LL ans=0; 66 For(i,0,k-1) (ans+=rs[i]*a[i+1]%p)%=p; 67 printf("%lld ",ans); 68 Formylove; 69 }