Submission #76083889

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Source Code Expand

#include <bits/stdc++.h>
#define int long long
#define ll long long
#define ull unsigned long long
#define inf 4e18
#define eps 1e-9
#define il inline
#define ls 2*k
#define rs 2*k+1
using namespace std;
const int N=2e5+5,M=1e7+5;
const int mod=998244353;
inline int read(){
    int x=0,f=1;
    char ch=getchar();
    while(ch<'0'||ch>'9'){
        if(ch=='-') f=-1;
        ch=getchar();
    }
    while(ch>='0' && ch<='9') x=x*10+ch-'0',ch=getchar();
    return x*f;
}
int n,val[N],a[N],siz[N],sum[N];
int jc[M],nijc[M],ans=1,lst[N];
inline int qpow(int x,int y){
    int res=1;
    while(y){
        if(y&1) res=res*x%mod;
        x=x*x%mod;
        y>>=1;
    }
    return res%mod;
}
vector<int>E[N];
inline bool check(int x,int fa){
	int f=1;
	sum[x]=a[x];
	siz[x]=val[x];
	for(auto to : E[x]){
		if(to==fa) continue;
		f|=check(to,x);
		sum[x]+=sum[to];
		siz[x]+=siz[to];
	}
	if(sum[x]>siz[x]) f=0;
	lst[x]=siz[x]-sum[x]+a[x];
	return f;
}
inline int C(int n_,int m_){
	if(m_>n_) return 0;
	n_%=mod; 
	int res=jc[(int)1e7];
	for(int i=1e7+1;i<=n_;i++)
		res=res*i%mod; 
	if(n_<=1e7) res=jc[n_];
	int ret=jc[(int)1e7];
	for(int i=1e7+1;i<=n_-m_;i++)
		ret=ret*i%mod;
	if(n_-m_<=1e7) ret=nijc[n_-m_];
	else ret=qpow(ret,mod-2)%mod;
	return res*nijc[m_]%mod*ret%mod;
}
inline void dfs(int x,int fa){
	for(auto to : E[x]){
		if(to==fa) continue;
		dfs(to,x);
	}
	ans=ans*C(lst[x],a[x])%mod;
//	cout<<x<<' '<<lst[x]<<' '<<a[x]<<'\n'; 
	return ;
}
signed main(){
	ios::sync_with_stdio(0);
	cin.tie(0); cout.tie(0);
	jc[0]=1,nijc[0]=1;
	for(int i=1;i<=1e7;i++){
		jc[i]=jc[i-1]*i%mod;
		nijc[i]=qpow(jc[i],mod-2);
	}
	int tc=1;
	while(tc--){
		cin>>n;
		for(int i=2,x;i<=n;i++){
			cin>>x;
			E[i].push_back(x);
			E[x].push_back(i);
		}
		for(int i=1;i<=n;i++) cin>>val[i];
		for(int i=1;i<=n;i++) cin>>a[i];
		if(!check(1,0)){
			cout<<0<<'\n';
			exit(0); 
		}
		dfs(1,0);
		cout<<ans<<'\n';
	}
	return 0;
}
/*
input： 
1
3 4 1
1 2 3
3 3 4 7 
6
output：
14

从大到小按位考虑，则如果能在不会让前面取不到的情况下取到，那么一定要操作。 
*/

Submission Info

Judge Result