Submission #1801061

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Source Code Expand

#include"bits/stdc++.h"


#define PB push_back
#define PF push_front
#define LB lower_bound
#define UB upper_bound
#define fr(x) freopen(x,"r",stdin)
#define fw(x) freopen(x,"w",stdout)
#define iout(x) printf("%d\n",x)
#define lout(x) printf("%lld\n",x)
#define REP(x,l,u) for(int x = (l);x<=(u);x++)
#define RREP(x,l,u) for(int x = (l);x>=(u);x--)
#define mst(x,a) memset(x,a,sizeof(x))
#define PII pair<int,int>
#define PLL pair<ll,ll>
#define MP make_pair
#define se second
#define fi first
#define dbg(x) cout<<#x<<" = "<<(x)<<endl;
#define sz(x) ((int)x.size())
#define cl(x) x.clear()

typedef  long long ll;
typedef unsigned long long ull;
typedef double db;
typedef long double ld;
using namespace std;

const int maxn = 100010;
const int mod = 1e9+7;
const int MAX = 1000000010;
const double eps = 1e-6;
const double PI = acos(-1);

template<typename T> inline void read(T &x){
x=0;T f=1;char ch;do{ch=getchar();if(ch=='-')f=-1;}while(ch<'0'||ch>'9');do x=x*10+ch-'0',ch=getchar();while(ch<='9'&&ch>='0');x*=f;
}

template<typename A,typename B> inline void read(A&x,B&y){read(x);read(y);}
template<typename A,typename B,typename C> inline void read(A&x,B&y,C&z){read(x);read(y);read(z);}
template<typename A,typename B,typename C,typename D> inline void read(A&x,B&y,C&z,D&w){read(x);read(y);read(z);read(w);}
template<typename A,typename B> inline A fexp(A x,B p){A ans=1;for(;p;p>>=1,x=1LL*x*x%mod)if(p&1)ans=1LL*ans*x%mod;return ans;}
template<typename A,typename B> inline A fexp(A x,B p,A mo){A ans=1;for(;p;p>>=1,x=1LL*x*x%mo)if(p&1)ans=1LL*ans*x%mo;return ans;}

int n,m;

struct Mat{
	int a[3][3];
	void clear(){memset(a,0,sizeof(a));REP(i,0,2)a[i][i]=1;}
}x,y,ans,z;

Mat mul(Mat x,Mat y){
	Mat ans;
	memset(ans.a,0,sizeof(ans.a));
	REP(i,0,2)REP(j,0,2)REP(k,0,2)ans.a[i][j]=(1ll*x.a[i][k]*y.a[k][j]+ans.a[i][j])%mod;
	return ans;
}

Mat Exp(int p){
	Mat ans;ans.clear();
	Mat t=x;
	for(;p;p>>=1,t=mul(t,t))if(p&1)ans=mul(ans,t);
	return ans;
}

void Work(){
	ans.clear();
	int lst=0;
	REP(i,1,m){
		int p;read(p);
		y=Exp(p-lst-1);
		lst=p;
		ans=mul(ans,y);
		ans=mul(ans,z);
	}
	y=Exp(n-lst);
	ans=mul(ans,y);
	iout(ans.a[0][2]);
}

void Init(){
	read(n,m);
	x.a[0][0]=2;x.a[0][1]=2;x.a[0][2]=1;
	x.a[1][0]=1;x.a[1][1]=1;x.a[1][2]=1;
	x.a[2][0]=1;x.a[2][2]=1;
	z.a[0][0]=1;z.a[0][1]=2;z.a[0][2]=1;
	z.a[1][1]=1;z.a[1][2]=1;
	z.a[2][2]=1;
}

int main(){
	Init();
	Work();
	return 0;
}

Submission Info

Judge Result