矩阵快速幂(斐波那契数列)

#include <iostream>#include <vector>using namespace std;typedef long long ll;typedef vector<ll> vec;typedef vector<vec> mat;const ll mod = 1e9+9;mat mul(mat& A, mat &B){    mat C(A.size(),vec(B[0].size()));    for(int i = 0; i < A.size(); ++i)        for(int k = 0; k < B.size(); ++k)            for(int j = 0; j < B[0].size(); ++j)                C[i][j] = (C[i][j]+A[i][k]*B[k][j])%mod;    return C;}mat pow(mat A, ll n){    mat B(A.size(),vec(A.size()));    for(int i = 0; i < A.size(); ++i)        B[i][i] = 1;    while(n > 0)    {        if(n&1) B = mul(B,A);        A = mul(A,A);        n >>= 1;    }    return B;}void solve(ll n){    mat A(2,vec(2));    A[0][0] = 1;    A[0][1] = 1;    A[1][0] = 1;    A[1][1] = 0;    A = pow(A,n);    cout << A[1][0] << endl;}int main(){    ll n;    cin >> n;    solve(n);    return 0;}