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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. const int MAXN = 100005;
  5. vector<int> adj[MAXN];
  6. long long dp0[MAXN], dp1[MAXN];
  7.  
  8. void dfs(int u, int p) {
  9.     dp0[u] = 0;
  10.     dp1[u] = 1;
  11.     for (int v : adj[u]) {
  12.         if (v == p) continue;
  13.         dfs(v, u);
  14.         dp0[u] += dp1[v];
  15.         dp1[u] += min(dp0[v], dp1[v]);
  16.     }
  17. }
  18.  
  19. int main() {
  20.     ios::sync_with_stdio(false);
  21.     cin.tie(nullptr);
  22.  
  23.     int n; 
  24.     if(!(cin >> n)) return 0;
  25.     for (int i = 1; i <= n; ++i) adj[i].clear();
  26.     for (int i = 0; i < n - 1; ++i) {
  27.         int u, v; cin >> u >> v;
  28.         adj[u].push_back(v);
  29.         adj[v].push_back(u);
  30.     }
  31.     dfs(1, -1);
  32.     cout << min(dp0[1], dp1[1]) << "\n";
  33.     return 0;
  34. }
  35.  
Success #stdin #stdout 0.01s 5948KB
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https://ideone.com/yLWHTK
language:
C++14 (gcc 8.3)
created:
16 days ago
visibility:
public

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