Course Requirements

    1#include <bits/stdc++.h>
    2using namespace std;
    3int main(){
    4    ios::sync_with_stdio(0); cin.tie(0);
    5    int n; cin >> n;
    6    vector<vector<int>> adj(n);
    7    vector<int> indegree(n);
    8    for(int i = 0; i < n; i++){
    9        int c; cin >> c;
    10        for(int j = 0; j < c; j++){
    11            int con; cin >> con;
    12            con--;
    13            indegree[i]++;
    14            adj[con].push_back(i);
    15        }
    16    }
    17    queue<int> q;
    18    vector<int> ans;
    19    for(int i = 0; i < indegree.size(); i++){
    20        if(indegree[i] == 0) q.push(i);
    21    } 
    22    while(!q.empty()){
    23        int cur = q.front(); q.pop();
    24        ans.push_back(cur);
    25        for(int nxt : adj[cur]){
    26            if(--indegree[nxt] == 0) q.push(nxt);
    27        }
    28    }
    29    for(int i = 0; i < ans.size(); i++){
    30        cout << ans[i] + 1 << " \n"[i == ans.size() - 1];
    31    }
    32    return 0;
    33}