python/TangDou/AcWing/TopSort/1191_TopSort.cpp

#include <bits/stdc++.h>
using namespace std;

const int N = 110, M = N * N;

int n;
int din[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++;
}
vector<int> path;
// 求拓扑序的模板
/*
①　所有入度为0的点入队列
②  队头元素出队，遍历它相临的点，并且将相临的点入度-1
③  如果减1后的入度为0，则此点入队列，意味着它的前序依赖已完成
*/
void topsort() {
    queue<int> q;
    // 所有入度为0的入队列
    for (int i = 1; i <= n; i++)
        if (din[i] == 0) q.push(i);

    while (q.size()) {
        int u = q.front();
        q.pop();
        path.push_back(u);
        for (int i = h[u]; ~i; i = ne[i]) {
            int v = e[i];
            din[v]--;
            if (din[v] == 0) q.push(v);
        }
    }
}

int main() {
    memset(h, -1, sizeof h);
    scanf("%d", &n);
    for (int a = 1; a <= n; a++) {
        int b;
        while (scanf("%d", &b), b) { // b==0时结束读入
            add(a, b);
            din[b]++; // 入度++
        }
    }
    // 拓扑序
    topsort();
    // 输出任意一组拓扑序
    for (int i = 0; i < n; i++) printf("%d ", path[i]);
    return 0;
}