给大家写一种用字典和vector 记录边和入度信息的写法，感觉自己不太适应写一个很大的数组来记的写法

C++ 代码

#include<iostream>
#include<unordered_map>
#include<vector>
#include<queue>
using namespace std;


int main(){
    int m,n,node;
    cin >> n >> m;
    unordered_map<int,int> indegree;
    unordered_map<int,vector<int>> pre;
    vector<int> res;
    for (int i=0;i<m;i++)
    {
        int x,y;
        cin >> x >> y;
        indegree[y] +=1;
        pre[x].push_back(y);
    }
    queue<int> q;
    for(int i=1;i<=n;i++)
    {
        if (!indegree.count(i))
        {
            indegree[i] = 0;
            q.push(i);
        }
    }
    while(q.size())
    {
        node = q.front();
        res.push_back(node);
        q.pop();
        for (auto neighbor:pre[node])
        {
            indegree[neighbor]--;
            if (indegree[neighbor]==0) q.push(neighbor);
        }
    }
    if (res.size()!=n) cout << -1;
    else{
        for (int i=0;i<res.size();i++)
        {
            cout << res[i] << ' ';
        }
    }
    return 0;   

}