样例过了，检查了114514遍，却还是TLE+WA，什么情况？

#include<bits/stdc++.h>
#define mod 1000000007
#define N 110

using namespace std;

int read()
{
    int x = 0,f = 1;
    char c = getchar();
    while(c<'0' || c>'9')
	{
        if(c=='-') f = -1;
        c = getchar();
    }
    while(c>='0' && c<='9')
	{
        x = (x<<3)+(x<<1)+(c^48);
        c = getchar();
    }
    return x*f;
}

int n,k;

struct rec
{
    int a[N][N];
    rec()
    {
    	memset(a,0,sizeof(a));
    }
    rec operator *(rec b)
    {
        rec p;
        for (int i=1;i<=n;i++)
            for (int j=1;j<=n;j++)
                for (int k=1;k<=n;k++)
                    p.a[i][j] = (p.a[i][j]+a[i][k]*b.a[k][j])%mod;
        return p;
    }
}a;

rec poww(int k)
{
    rec ans;
	for (int i=1;i<=n;i++)
		ans.a[i][i]=1;
	rec s=a;
	while(k)
	{
		if (k&1) ans = ans*s;
		s = s*s;
		k >>= 1;
	}
	return ans;
}

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