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- #include <iostream>
- #include <vector>
- #include <set>
- #include <cstring>
- #include <queue>
- #include <cmath>
- #include <algorithm>
- #include <stack>
- using namespace std;
- const int maxn = 1e5 + 10;
- int n, m;
- vector<int> graph[maxn], reversed_graph[maxn];
- bool visited[maxn];
- stack<int> st;
- void topological_sort(int node) {
- visited[node] = true;
- for(int i = 0; i < (int) graph[node].size(); i++) {
- int neighbour = graph[node][i];
- if(!visited[neighbour]) {
- topological_sort(neighbour);
- }
- }
- st.push(node);
- }
- void dfs(int node) {
- cout << node + 1 << " " ;
- visited[node] = true;
- for(int i = 0; i < (int) reversed_graph[node].size(); i++) {
- int neighbour = reversed_graph[node][i];
- if(!visited[neighbour]) {
- dfs(neighbour);
- }
- }
- }
- int main() {
- cin >> n >> m;
- for(int i = 0; i < m; i++) {
- int a, b;
- cin >> a>> b;
- a--;
- b--;
- graph[a].push_back(b);
- reversed_graph[b].push_back(a);
- }
- memset(visited, false, sizeof visited);
- for(int i = 0; i < n; i++) {
- if(!visited[i]) {
- topological_sort(i);
- }
- }
- memset(visited, false, sizeof visited);
- while(!st.empty()) {
- int node = st.top();
- st.pop();
- if(!visited[node]) {
- dfs(node);
- cout << endl;
- }
- }
- return 0;
- }
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