矩阵快速幂 求斐波那契第N项

#include<cstdio>
#include<algorithm>
#include<cstring>
#include<iostream>
using namespace std;

const int M = 1e9+7;

struct Matrix {
    long long a[2][2];
    Matrix() {
        memset(a, 0, sizeof(a));
    }
    Matrix operator * (const Matrix y) {
        Matrix ans;
        for(int i = 0; i <= 1; i++)
            for(int j = 0; j <= 1; j++)    
                for(int k = 0; k <= 1; k++)    
                    ans.a[i][j] += a[i][k]*y.a[k][j];
        for(int i = 0; i <= 1; i++)
            for(int j = 0; j <= 1; j++)
                ans.a[i][j] %= M;
        return ans;
    }
    void operator = (const Matrix b) {
        for(int i = 0; i <= 1; i++)
            for(int j = 0; j <= 1; j++)
                a[i][j] = b.a[i][j];
    }
};

int solve(long long x) {
    Matrix ans, trs;
    ans.a[0][0] = ans.a[1][1] = 1;
    trs.a[0][0] = trs.a[1][0] = trs.a[0][1] = 1;
    while(x) {
        if(x&1) 
            ans = ans*trs;
        trs = trs*trs;
        x >>= 1;
    }
    return ans.a[0][0];
}

int main() {
    int n;
    scanf("%d", &n);
    cout << solve(n-1) << endl;
    return 0;
}

 POJ 3070