UVA 10689 Yet another Number Sequence 矩阵快速幂 水呀水

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

typedef long long ll;
const int N = 4;
int Mod;
int msize;

struct Mat
{
int mat

;
};

Mat operator *(Mat a, Mat b)
{
Mat c;
memset(c.mat, 0, sizeof(c.mat));
for(int k = 0; k < msize; ++k)
for(int i = 0; i < msize; ++i)
if(a.mat[i][k])
for(int j = 0; j < msize; ++j)
if(b.mat[k][j])
c.mat[i][j] = ((ll)a.mat[i][k] * b.mat[k][j] + c.mat[i][j])%Mod;
return c;
}

Mat operator ^(Mat a, int k)
{
Mat c;
memset(c.mat,0,sizeof(c.mat));
for(int i = 0; i < msize; ++i)
c.mat[i][i]=1;
for(; k; k >>= 1)
{
if(k&1) c = c*a;
a = a*a;
}
return c;
}

int main()
{
//    freopen("in.txt", "r", stdin);
int t, a, b, n, m;
msize = 2;
scanf("%d", &t);
while(t--)
{
scanf("%d%d%d%d", &a, &b, &n, &m);
Mod = 1;
while(m--) Mod *= 10;
if(n == 0)
{
printf("%d\n", a%Mod);
continue;
}
Mat A;
A.mat[0][0] = 1, A.mat[0][1] = 1;
A.mat[1][0] = 1, A.mat[1][1] = 0;
A = A^(n-1);
printf("%d\n", (A.mat[0][0]*b + A.mat[0][1]*a)%Mod);
}
return 0;
}