HDU - 1575 Tr A 纯矩阵快速幂

解题思路：int型的注意，+= (a * b) % 9973时小心溢出了

#include<cstdio>
#include<cstring>
using namespace std;
#define maxn 10
#define mod 9973
typedef long long ll;
struct Matrix{
    ll mat[maxn][maxn];
}a, b, tmp;
int n, k;

Matrix matrixMul(Matrix aa, Matrix bb) {
    for(int i = 0; i < n; i++)
        for(int j = 0; j < n; j++) {
            tmp.mat[i][j] = 0;
            for(int k = 0; k < n; k++)
                tmp.mat[i][j] += (aa.mat[i][k] * bb.mat[k][j]) % mod;
        }
    return tmp;
}

void solve() {
    while(k) {
        if(k & 1)
            b = matrixMul(b,a);
        a = matrixMul(a,a);
        k >>= 1;
    }
}

int main() {
    int test;
    scanf("%d", &test);
    while(test--) {
        scanf("%d%d", &n, &k);
        for(int i = 0; i < n; i++)
            for(int j = 0; j < n; j++) {
                b.mat[i][j] = 0;
                scanf("%I64d", &a.mat[i][j]);
            }
        for(int i = 0; i < n; i++)
            b.mat[i][i] = 1;
        solve();
        ll ans = 0;
        for(int i = 0; i < n; i++)
            ans += b.mat[i][i];
        printf("%I64d\n", ans % mod);
    }
    return 0;
}