#include<bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 5;
struct node
{
int to, next;
}e[maxn << 1];
int head[maxn], in[maxn], n, m, cnt;
void init() {
memset(head, -1, sizeof(head));
memset(in, 0, sizeof(in));
memset(e, 0, sizeof(e));
cnt = 0;
}
void add (int from, int to) {
e[++cnt].to = to;
e[cnt].next = head[from];
head[from] = cnt;
}
void topsort() {
priority_queue <int, vector <int>, greater <int> > q;
vector <int> ans;
for (int i = 1; i <= n; i++) {
if (!in[i]) q.push(i);
}
while (!q.empty()) {
int u = q.top();
q.pop();
ans.push_back(u);
for (int i = head[u]; i != -1; i = e[i].next) {
int v = e[i].to;
in[v]--;
if (!in[v]) q.push(v);
}
}
for (int i = 0; i < ans.size() - 1; i++) cout << ans[i] << " ";
cout << ans[ans.size() - 1] << endl;
}
int main()
{
while (cin >> n >> m) {
init();
for (int i = 0; i < m; i++) {
int ui, vi;
cin >> ui >> vi;
add (ui, vi);
in[vi]++;
}
topsort();
}
return 0;
}
拓扑排序模板题，注意多样例输出 和最后一个输出后面没有空格
