矩阵求斐波那契数列

#include <iostream>
#include <cstring>
using namespace std;
typedef long long ll;
const ll mod = 1e9 + 7;
ll n, sum;
struct Node
{
    ll a[2][2];
};
Node mut(Node x, Node y)
{
    Node ans;
    memset(ans.a, 0, sizeof(ans.a));
    for (ll i = 0; i < 2; i++)
        for (ll j = 0; j < 2; j++)
            for (ll k = 0; k < 2; k++)
                ans.a[i][j] = (ans.a[i][j] + x.a[i][k] * y.a[k][j]) % mod;
    return ans;
}
void qp(ll n)
{
    Node now, ans;
    now.a[0][0] = 1;
    now.a[0][1] = 1;
    now.a[1][0] = 1;
    now.a[1][1] = 0;
    memset(ans.a, 0, sizeof(ans.a));
    for (ll i = 0; i < 2; i++)
        ans.a[i][i] = 1;
    while (n)
    {
        if (n & 1)
            ans = mut(ans, now);
        now = mut(now, now);
        n = n >> 1;
    }
    cout <<(ans.a[0][1] % mod)<< '\n';
}
int main()
{
    while(cin>>n){
    qp(n);}
    return 0;
}