标签:algorithm int seq 线性 def scan ring names vector
找线性规律万能模板
(1) n是指要找该数列的第n项
(2) 往vec中放入该数列前几项的值,越多越精确
#include<set> #include<cmath> #include<vector> #include<string> #include<cstdio> #include<cassert> #include<cstring> #include<algorithm> using namespace std; #define rep(i,a,n) for (ll i=a;i<n;i++) #define per(i,a,n) for (ll i=n-1;i>=a;i--) #define fi first #define se second #define pb push_back #define mp make_pair #define SZ(x) ((ll)(x).size()) #define all(x) (x).begin(),(x).end() typedef long long ll; typedef vector<ll> VI; typedef pair<ll, ll> PII; const ll mod=1000000007; ll powmod(ll a, ll b) { ll res=1; a%=mod; assert(b>=0); for(;b;b>>=1) { if(b&1) res=res*a%mod; a=a*a%mod; } return res; } ll _,n; namespace linear_seq { const ll N=10010; ll res[N],base[N],_c[N],_md[N]; vector<ll>Md; void mul(ll*a,ll*b,ll k) { rep(i,0,k+k) _c[i]=0; rep(i,0,k) if(a[i]) rep(j,0,k) _c[i+j]=(_c[i+j]+a[i]*b[j])%mod; for(ll i=k+k-1;i>=k;i--) if(_c[i]) rep(j,0,SZ(Md)) _c[i-k+Md[j]]=(_c[i-k+Md[j]]-_c[i]*_md[Md[j]])%mod; rep(i,0,k) a[i]=_c[i]; } ll solve(ll n, VI a, VI b) { ll ans=0,pnt=0; ll k=SZ(a); assert(SZ(a)==SZ(b)); rep(i,0,k) _md[k-1-i]=-a[i]; _md[k]=1; Md.clear(); rep(i,0,k) if(_md[i]!=0) Md.push_back(i); rep(i,0,k) res[i]=base[i]=0; res[0]=1; while((1ll<<pnt)<=n) pnt++; for(ll p=pnt;p>=0;p--) { mul(res,res,k); if((n>>p)&1) { for(ll i=k-1;i>=0;i--) res[i+1]=res[i]; res[0]=0; rep(j,0,SZ(Md)) res[Md[j]]=(res[Md[j]]-res[k]*_md[Md[j]])%mod; } } rep(i,0,k) ans=(ans+res[i]*b[i])%mod; if(ans<0) ans+=mod; return ans; } VI BM(VI s) { VI C(1,1),B(1,1); ll L=0,m=1,b=1; rep(n,0,SZ(s)) { ll d=0; rep(i,0,L+1) d=(d+(ll)C[i]*s[n-i])%mod; if(d==0) ++m; else if(2*L<=n) { VI T=C; ll c=mod-d*powmod(b,mod-2)%mod; while(SZ(C)<SZ(B)+m) C.pb(0); rep(i,0,SZ(B)) C[i+m]=(C[i+m]+c*B[i])%mod; L=n+1-L; B=T; b=d; m=1; } else { ll c=mod-d*powmod(b,mod-2)%mod; while(SZ(C)<SZ(B)+m) C.pb(0); rep(i,0,SZ(B)) C[i+m]=(C[i+m]+c*B[i])%mod; ++m; } } return C; } ll gao(VI a,ll n) { VI c=BM(a); c.erase(c.begin()); rep(i,0,SZ(c)) c[i]=(mod-c[i])%mod; return solve(n,c,VI(a.begin(),a.begin()+SZ(c))); } }; int main() { int T; scanf("%d",&T); while(T--) { scanf("%lld", &n); VI vec; vec.push_back(1); vec.push_back(1); vec.push_back(2); vec.push_back(3); vec.push_back(5); vec.push_back(8); vec.push_back(13); printf("%lld\n", linear_seq::gao(vec, n - 1)%mod); } }
标签:algorithm int seq 线性 def scan ring names vector
原文地址:https://www.cnblogs.com/kannyi/p/9803415.html