Topsort 基本模板

仅作记录，拓扑模板

//
// Created by 29273 on 2022-03-16.
//
#include "bits/stdc++.h"

using namespace std;
const int maxN = 1e4 + 10;
vector<int> V[maxN];
vector<int> ans;
int in[maxN];
int n, x, y, m;

void topSort() {
    queue<int> Q;
    for (int i = 1; i <= n; ++i) {
        if (!in[i]) Q.push(i);
    }
    while (Q.size()) {
        int top = Q.front();
        Q.pop();
        ans.push_back(top);
        for (int i = 0; i < V[top].size(); ++i) {
            int xx = V[top][i];
            in[xx]--;
            if (!in[xx]) Q.push(xx);
        }
    }
    if (ans.size() == n) printf("1\n");
    else printf("0\n");
}

int main() {
    cin >> n >> m;
    while (m--) {
        cin >> x >> y;
        V[x].push_back(y);
        in[y]++;
    }
    topSort();
    for (int i = 0; i < ans.size(); ++i) {
        cout << ans[i] << endl;
    }
    return 0;
}
/*
 * 6 7
1 2
1 3
2 4
3 4
4 5
4 6
5 6
 */

简单优先队列版本

//
// Created by 29273 on 2022-03-16.
//
#include "bits/stdc++.h"

using namespace std;
const int maxN = 1e4 + 10;
vector<int> V[maxN];
vector<int> ans;
int in[maxN];
int n, x, y, m;

void topSort() {
//    queue<int> Q;
    priority_queue<int, vector<int>, less<int> > Q;
    for (int i = 1; i <= n; ++i) {
        if (!in[i]) Q.push(i);
    }
    while (Q.size()) {
        int top = Q.top();
        Q.pop();
        ans.push_back(top);
        for (int i = 0; i < V[top].size(); ++i) {
            int xx = V[top][i];
            in[xx]--;
            if (!in[xx]) Q.push(xx);
        }
    }
    if (ans.size() == n) printf("1\n");
    else printf("0\n");
}

int main() {
    cin >> n >> m;
    while (m--) {
        cin >> x >> y;
        V[x].push_back(y);
        in[y]++;
    }
    topSort();
    for (int i = 0; i < ans.size(); ++i) {
        cout << ans[i] << endl;
    }
    return 0;
}
/*
 * 6 7
1 2
1 3
2 4
3 4
4 5
4 6
5 6
 */