求矩阵的模n^3logn

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <vector>

using namespace std;
typedef __int64 lld;
const int MOD = 998244353;
const int N = 20;

struct Mat {
    lld a[N][N];
    void init(int _a[N][N], int n) {
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                a[i][j] = _a[i][j];
            }
        }
    }

    lld * operator [] (int x) {
        return a[x];
    }
}AC, C;

lld Det(Mat &A, int n) {
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            C[i][j] = A[i][j] % MOD;
        }
    }
    lld ret = 1;
    for (int i = 0; i < n; i++) {
        for (int j = i + 1; j < n; j++) {
            while (C[j][i]) {
                for (int t = C[i][i] / C[j][i], k = 0; k < n; k++) {
                    printf("t  = %d
", t);
                    C[i][k] = (C[i][k] - C[j][k] * t) % MOD;
                    swap(C[i][k], C[j][k]);
                }
                ret = - ret;
            }
            for(int o = 0; o < n; o ++){
                for(int z = 0; z < n; z ++) printf("%d ", C[o][z]); printf("
");
            }
        }
        if (C[i][i] == 0) return 0;
        ret = ret * C[i][i] % MOD;
    }
    return ret;
}


int main(){
    int a[N][N] = {
        {2,3,4},
        {3,4,2},
        {4,2,3}
    };
    int cur = 4;
    AC.init(a, cur - 1);
    printf("%I64d
", Det(AC, cur - 1));
}