记录编号	594751	评测结果	AAAAAAAAAA
题目名称	森林大礼包	最终得分	100
用户昵称	健康铀	是否通过	通过
代码语言	C++	运行时间	0.586 s
提交时间	2024-10-04 21:09:06	内存使用	11.70 MiB

#include<bits/stdc++.h>
using namespace std;  
const int N = 5e5 + 10;  
#define MOD 1000000007  
#define LL long long  
LL n, idx = 1, head[N], sr[N], res[N];  
struct Edge {  
    LL u, v, next;  
}ed[N<<1];  
queue<LL> q;  
inline LL get() {  
    LL num = 0;   
    char c = getchar();  
    while (c < '0' || c > '9') c = getchar();  
    while (c >= '0' && c <= '9') num = num * 10 + c - '0', c = getchar();  
    return num;  
}  
inline void add(LL u, LL v) {  
    ed[idx].v = v;  
    ed[idx].next = head[u];  
    head[u] = idx++;  
}   
int main() {  
    freopen("three_squirrels.in", "r", stdin);  
    freopen("three_squirrels.out", "w", stdout);  
    n=get();  
    fill(head, head+n+1, -1);  
    for (LL i=1;i<=n;i++) {  
        sr[i]=get();  
        for(LL j=0;j<sr[i];j++)   
        add(get(),i);  
    }  
    for (LL i=head[0];i;i=ed[i].next) {  
        LL v=ed[i].v;  
        sr[v]--;  
        res[v]++;  
        if(!sr[v])
		q.push(v);  
    }  
    while(!q.empty()) {  
        LL cur=q.front();  
        q.pop();  
        for (LL i=head[cur];i;i=ed[i].next) {  
            LL v=ed[i].v;  
            sr[v]--;  
            res[v]=(res[v]+res[cur])%MOD;  
            if(!sr[v])
			q.push(v);  
        }  
    } 
    printf("%lld",res[n]);  
    return 0;  
}