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  1. #include <bits/stdc++.h>
  2.  
  3. using namespace std;
  4.  
  5. vector<int> adj[100111];
  6. int res;
  7. bool visited[100111];
  8. int dp[100111];
  9. int m, n;
  10.  
  11. int DFS(int u) {
  12.     if (dp[u]) return dp[u];
  13.  
  14.     for (int i = 0; i < adj[u].size(); i += 1) {
  15.         int v = adj[u][i];
  16.         dp[u] = max(dp[u], DFS(v) + 1);
  17.     }
  18.  
  19.     return dp[u];
  20. }
  21.  
  22. int32_t main() {
  23.     ios_base::sync_with_stdio(false);
  24.     cin.tie(NULL);
  25.  
  26.     cin >> m >> n;
  27.     for (int i = 1, u, v; i <= n; i += 1) {
  28.         cin >> u >> v;
  29.         adj[u].push_back(v);
  30.     }
  31.  
  32.     for (int i = 1; i <= m; i += 1) {
  33.         res = max(res, DFS(i));
  34.     }
  35.  
  36.     cout << res;
  37.     return 0;
  38. }
Success #stdin #stdout 0.01s 6080KB
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https://ideone.com/5d6Has
language:
C++14 (gcc 8.3)
created:
9 days ago
visibility:
public

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