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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. const int N = 2e5 + 5;
  5. int deg[N];
  6. int A[N];
  7. vector<int> adj[N];
  8. int n, m;
  9.  
  10. int dfs(int u, int k, int p = -1) {
  11. 	// leaf node
  12. 	if (deg[u] == 1 && p != -1 && k <= m) {
  13. 		return 1;
  14. 	}
  15.  
  16. 	// more than m consecutive cats on current path
  17. 	if (k > m) {
  18. 		return 0;
  19. 	}
  20.  
  21. 	int ret = 0;
  22. 	for (auto& v : adj[u]) {
  23. 		if (v == p) continue;
  24. 		if (A[v]) {
  25. 			ret += dfs(v, k + 1, u);
  26. 		} else {
  27. 			ret += dfs(v, 0, u);
  28. 		}
  29. 	}
  30. 	return ret;
  31. }
  32.  
  33. int main() {
  34. 	cin >> n >> m;
  35. 	for (int i = 1; i <= n; i++) {
  36. 		cin >> A[i];
  37. 	}
  38. 	for (int i = 0; i < n - 1; i++) {
  39. 		int u, v;
  40. 		cin >> u >> v;
  41. 		deg[u]++;
  42. 		deg[v]++;
  43. 		adj[u].push_back(v);
  44. 		adj[v].push_back(u);
  45. 	}	
  46. 	cout << dfs(1, A[1]) << endl;
  47. }
Success #stdin #stdout 0.01s 8540KB
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https://ideone.com/ejDU6Q
language:
C++14 (gcc 8.3)
created:
30 days ago
visibility:
public

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