백준 1766 C++ 풀이

#include <iostream>
#include <algorithm>
#include <queue>
#include <math.h>
#include <climits>
#include <map>
using namespace std;
int degree[32001];
vector<int> buffer[32001];

int main(){
    cin.tie(NULL);
    ios::sync_with_stdio(false);
    int n, m;
    cin >> n >> m;
    for (auto i =0; i<m; i++){
        int from, to;
        cin >> from >> to;
        buffer[from-1].push_back(to-1);
        degree[to-1]++;
    }
    priority_queue<int, vector<int>, greater<int>> q;

    for (auto i =0; i<n; i++){
        if (degree[i] == 0){
           // cout << i << 'a' << '\n';
            q.push(i);
        }
    }

    while (!q.empty()){
        int top = q.top();
        cout << top+1 << ' ';
        q.pop();
        for (int to : buffer[top]){
            degree[to]--;
            if (degree[to] == 0){
                q.push(to);
            }
        }
    }

    return 0;
}