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Codeforces Round #203 (Div. 2)B Resort

2024-09-10 01:45:30   221人阅读

Resort
Time Limit:2000MS     Memory Limit:262144KB     64bit IO Format:%I64d & %I64u
Submit Status Practice CodeForces 350B

Description

Valera‘s finally decided to go on holiday! He packed up and headed for a ski resort.

Valera‘s fancied a ski trip but he soon realized that he could get lost in this new place. Somebody gave him a useful hint: the resort has nobjects (we will consider the objects indexed in some way by integers from 1 to n), each object is either a hotel or a mountain.

Valera has also found out that the ski resort had multiple ski tracks. Specifically, for each object v, the resort has at most one object u, such that there is a ski track built from object u to object v. We also know that no hotel has got a ski track leading from the hotel to some object.

Valera is afraid of getting lost on the resort. So he wants you to come up with a path he would walk along. The path must consist of objects v1, v2, ..., vk (k ≥ 1) and meet the following conditions:

  1. Objects with numbers v1, v2, ..., vk - 1 are mountains and the object with number vk is the hotel.
  2. For any integer i(1 ≤ i < k), there is exactly one ski track leading from object vi. This track goes to object vi + 1.
  3. The path contains as many objects as possible (k is maximal).

Help Valera. Find such path that meets all the criteria of our hero!

Input

The first line contains integer n (1 ≤ n ≤ 105) — the number of objects.

The second line contains n space-separated integers type1, type2, ..., typen — the types of the objects. If typei equals zero, then the i-th object is the mountain. If typei equals one, then the i-th object is the hotel. It is guaranteed that at least one object is a hotel.

The third line of the input contains n space-separated integers a1, a2, ..., an (0 ≤ ai ≤ n) — the description of the ski tracks. If number ai equals zero, then there is no such object v, that has a ski track built from v to i. If number ai doesn‘t equal zero, that means that there is a track built from object ai to object i.

Output

In the first line print k — the maximum possible path length for Valera. In the second line print k integers v1, v2, ..., vk — the path. If there are multiple solutions, you can print any of them.

Sample Input

Input
5
0 0 0 0 1
0 1 2 3 4
Output
5
1 2 3 4 5
Input
5
0 0 1 0 1
0 1 2 2 4
Output
2
4 5
Input
4
1 0 0 0
2 3 4 2
Output
1
1
/*竟然看漏了一个隐藏条件，每个点的入度只能为零*/#include <bits/stdc++.h>#define INF 0x3f3f3f3fusing namespace std;int val[100005];vector<int> edge[100005];int vis[100005];vector<int> path[100005];int n;int a;//每个点只可能有一个入度int main(){    // freopen("in.txt","r",stdin);    scanf("%d",&n);    for(int i=1;i<=n;i++){        scanf("%d",&val[i]);    }    for(int i=1;i<=n;i++){        scanf("%d",&a);        if(a){            edge[i].push_back(a);//建图            vis[a]++;        }    }    //从1开始向前找    for(int i=1;i<=n;i++){        if(val[i]){            path[i].push_back(i);            if(edge[i].size()==0){                continue;            }            int pos=edge[i][0];            while(true){                if(val[pos]==1){//如果这一步是1的话肯定是不行的                    break;                }                if(vis[pos]>1){//如果这一步有两个出度也是不行的                    break;                }                if(edge[pos].size()==0){//如果没有下一步了                    path[i].push_back(pos);                    break;                }                path[i].push_back(pos);                pos=edge[pos][0];            }        }    }    int maxn=-1;    for(int i=1;i<=n;i++){        maxn=max((int)path[i].size(),maxn);    }    for(int i=1;i<=n;i++){        if(path[i].size()==maxn){            printf("%d\n",maxn);            for(int j=path[i].size()-1;j>=0;j--){                printf(j==path[i].size()-1?"%d":" %d",path[i][j]);            }            printf("\n");            break;        }    }    return 0;}

 

Codeforces Round #203 (Div. 2)B Resort


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