python/TangDou/CSP-J/J-2023/HDU4857.cpp

#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5, M = N << 1;

int n, m, ans[N], al;
int in[N];

// 链式前向星
int e[M], h[N], idx, w[M], ne[M];
void add(int a, int b, int c = 0) {
    e[idx] = b, ne[idx] = h[a], w[idx] = c, h[a] = idx++;
}

void topsort() {
    priority_queue<int> q;
    for (int i = 1; i <= n; i++)
        if (in[i] == 0) q.push(i);

    while (q.size()) {
        int u = q.top();
        q.pop();
        ans[al++] = u;
        for (int i = h[u]; ~i; i = ne[i]) {
            int j = e[i];
            in[j]--;
            if (in[j] == 0) q.push(j);
        }
    }
}
void solve() {
    cin >> n >> m;
    al = 0, idx = 0;
    memset(h, -1, sizeof h);

    while (m--) {
        int u, v;
        cin >> u >> v;
        add(v, u);
        in[u]++;
    }
    topsort();
    for (int i = al - 1; i >= 0; i--) {
        cout << ans[i];
        if (i != 0)
            cout << ' ';
        else
            cout << endl;
    }
}
int main() {
    ios::sync_with_stdio(false), cin.tie(0);
    int T;
    cin >> T;
    while (T--) solve();
    return 0;
}