题解有误&编译有毒？

题解给出的式子有误，应该是这样的：
设：

t=2\sum\limits_{i=1}^n3^{n(n-i)+i}(-1)^{i+1}\text{C}(n,i)

那么：

\text{ans} = t+3\sum\limits_{i=0}^{n-1}(-1)^{i+1}((1-3^i)^n-(-3^i)^n)\text{C}(n,i)

还有编译好像有毒？本机没问题，结果提交CE？
code：

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<iostream>
#include<bitset>
#define N 1000003
#define inf 0x3f3f3f3f
#define int long long
#define p 998244353
using namespace std;

int pw[N],inv[N],fac[N];
int n,ans,ng,t,ad,rs;

inline void read(int &x);
void print(int x);
void init();
inline int C(int x,int y);
inline int pow(int a,int t);

signed main(){
    read(n);
    init();
    for(int i=0;i<n;++i){
        ng = (i&1)?1:-1;
        t = pow(1-pw[i],n)-pow(-pw[i],n);
        ad = (ng*t%p*C(n,i)%p+p)%p;
        ans = (ans+ad)%p;
    }
    ans = ans*3%p;
    for(int i=1;i<=n;++i)
        rs = (rs+pow(3,(n*(n-i)+i)%(p-1))*((i&1)?1:-1)%p*C(n,i)%p);
    rs = (rs%p+p)%p;
    rs = (rs<<1)%p;
    ans = (ans+rs)%p;
    print(ans);
    return 0;
}

inline int C(int x,int y){
    if(x<y) return 0;
    return fac[x]*inv[y]%p*inv[x-y]%p;
}

void init(){
    pw[0] = inv[1] = fac[0] = fac[1] = 1;
    pw[1] = 3;
    for(int i=2;i<=n;++i){
        fac[i] = fac[i-1]*i%p;
        inv[i] = (p-p/i)*inv[p%i]%p;
        pw[i] = pw[i-1]*3%p;
    }
    inv[0] = 1;
    for(int i=2;i<=n;++i)
        inv[i] = inv[i]*inv[i-1]%p;
}

inline void read(int &x){
    x = 0;
    char c = getchar();
    while(c<'0'||c>'9') c = getchar();
    while(c>='0'&&c<='9'){
        x = (x<<3)+(x<<1)+(c^48);
        c = getchar();
    }
}

void print(int x){
    if(x>9) print(x/10);
    putchar(x%10+'0');
}

inline int pow(int a,int t){
    int res = 1;
    while(t){
        if(t&1) res = res*a%p;
        a = a*a%p;
        t >>= 1;
    }
    return res;
}