洛谷P3390 【模板】矩阵快速幂 题解 矩阵快速幂模板题

题目链接：https://www.luogu.com.cn/problem/P3390

矩阵快速幂模板题。

示例程序：

#include <bits/stdc++.h>
using namespace std;
const int maxn = 105;
const long long mod = 1e9 + 7;

struct Matrix {
    int n, m;
    long long a[maxn][maxn];

    void init(int _n, int _m) {
        n = _n;
        m = _m;
        for (int i = 1; i <= n; i++)
            for (int j = 1; j <= m; j++)
                a[i][j] = 0;
    }

    Matrix operator * (const Matrix &b) const {
        Matrix res;
        res.init(n, b.m);
        for (int i = 1; i <= n; i++)
            for (int j = 1; j <= m; j++)
                for (int k = 1; k <= b.m; k++)
                    res.a[i][k] += a[i][j] * b.a[j][k],
                    res.a[i][k] %= mod;
        return res;
    }

    Matrix operator ^ (long long k) const {
        Matrix res, t;
        res.init(n, n);
        for (int i = 1; i <= n; i++)
            res.a[i][i] = 1;
        t.init(n, n);
        memcpy(t.a, a, sizeof a);
        for (; k; k >>= 1, t = t * t)
            if (k & 1ll)
                res = res * t;
        return res;
    }
} a;
int n;
long long k;

int main() {
    cin >> n >> k;
    a.init(n, n);
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= n; j++)
            cin >> a.a[i][j];
    a = a ^ k;
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= n; j++)
            cout << a.a[i][j] << " ";
        cout << endl;
    }
    return 0;
}