矩阵乘法解fibonacci斐波那契数列

#include <iostream>#include <cstdio>using namespace std;struct mat{    long long d[2][2];};mat operator *(const mat&a,const mat&b)//定义矩阵乘法{    mat ans;    for(int i=0;i<=1;i++)        for(int j=0;j<=1;j++)        {            ans.d[i][j]=0;            for(int k=0;k<=1;k++)                ans.d[i][j]+=a.d[i][k]*b.d[k][j];            ans.d[i][j]%=1000000007;        }    return ans;}mat one;mat poww(mat &a ,long long x)//算n次方{    mat ans;    if(x==0)    return one;    else    {        ans=poww(a,x/2);            ans=ans*ans;        if(x%2==1)//如果n是奇数则再乘一个a        {            ans=a*ans;        }    }    return ans;}int main(){    mat f;    one.d[0][0]=one.d[1][1]=1;    one.d[1][0]=one.d[0][1]=0;    f.d[0][0]=f.d[0][1]=f.d[1][0]=1;    f.d[1][1]=0;    long long n;    scanf("%lld",&n);    mat ans=poww(f,n);    printf("%d",ans.d[0][1]);}