C++11(clang++ 3.9) 解法, 执行用时: 10ms, 内存消耗: 412K, 提交时间: 2020-10-02 20:24:31

#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define f(i,a,b) for(int i=a;i<=b;i++)
inline ll r() {
	ll x=0,f=1;
	char c=getchar();
	while(c<'0'||c>'9'){if(c=='-')f=-1;c=getchar();}
	while(isdigit(c))x=x*10+c-'0',c=getchar();
	return x*f;
}
#define d r()
ll n;
ll fa[1010];
ll x[1010];
ll find(ll x){
	if(fa[x]==x)return x;
	else return fa[x]=find(fa[x]);
}
ll a[1010];
ll ans,cmp;
int main(){
	n=ans=d;
	f(i,1,n)fa[i]=i;
	f(i,1,n-3)x[i]=d;
	f(i,1,n-3){
		ll y=d;
		ll xx=find(x[i]),yy=find(y);
		if(xx!=yy)fa[xx]=yy;
	}
	f(i,1,n)a[find(i)]++;
	f(i,1,n)if(a[i])ans*=a[i],ans%=987654323,cmp++;
	if(cmp!=3)ans=0;
	printf("%lld",ans);
	return 0;
}