hdu 3519 Lucky Coins Sequence dp+矩阵连乘优化

#include 
#include 
#include 
#include 
#include 
#include 
using namespace std;
#define LL __int64
const int mod=1e4+7;
const int maxn=4;
struct matrix{
    int f[maxn][maxn];
};
matrix mul(matrix a,matrix b)
{
    matrix c;
    int i,j,k;
    memset(c.f,0,sizeof(c.f));
    for(k=0;k>1;
    }
    return s;
}
int pows(int a,int b)
{
    int s=1;
    while(b)
    {
        if(b&1)
            s=(s*a)%mod;
        a=(a*a)%mod;
        b=b>>1;
    }
    return s;
}
int main()
{
    int n;
    while(cin>>n)
    {
        matrix e;
        memset(e.f,0,sizeof(e.f));
        e.f[0][1]=e.f[0][2]=e.f[1][0]=e.f[1][3]=e.f[2][1]=e.f[3][0]=1;
        e=pow_mod(e,n-1);
        int ans=0;
        ans=(e.f[0][0]+e.f[1][0]+e.f[0][1]+e.f[1][1]+e.f[0][2]+e.f[1][2]+e.f[0][3]+e.f[1][3])%mod;
        ans=(pows(2,n)-ans+mod)%mod;
        cout<