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  1. #include<bits/stdc++.h>
  2. using namespace std;
  3.  
  4. using i64 = long long;
  5.  
  6. const int inf=1e9;
  7.  
  8. void bfs(int u, vector<vector<int>> &g, vector<int> &dist, vector<bool> &p, vector<int> &a) {
  9.     queue<int> q; q.push(u);
  10.     dist[u] = 0;
  11.     while (!q.empty()) {
  12.         int node = q.front(); q.pop();
  13.         if(p[node]) a.push_back(dist[node]);
  14.         for (auto &x: g[node]) {
  15.             if (dist[x] == -1) {
  16.                 dist[x] = dist[node] + 1; 
  17.                 q.push(x);
  18.             }
  19.         }
  20.     }
  21. }
  22.  
  23. void solve(){
  24.     int n,k; cin>>n>>k;
  25.  
  26.     vector<bool> p(n+1);
  27.     for(int i=0;i<k;i++) {
  28.         int x; cin>>x;
  29.         p[x]=true;
  30.     }
  31.     int root=1;
  32.     vector<vector<int>> g(n+1);
  33.     vector<int> dist(n+1,-1),mset,ans(n+1);
  34.  
  35.     for (int i = 0; i < n - 1; ++i) {
  36.         int u, v; cin >> u >> v; 
  37.         g[u].push_back(v);
  38.         g[v].push_back(u);
  39.     }
  40.     for (int i = 1; i <= n; ++i)
  41.         if (g[i].size() == 1)
  42.             root=i;
  43.  
  44.     bfs(root, g, dist, p, mset); 
  45.     sort(mset.begin(), mset.end());
  46.  
  47.     for (int i = 1; i <= n; ++i)
  48.         ans[i] = max(abs(dist[i] - mset.front()), abs(dist[i] - mset.back()));
  49.  
  50.     cout << *min_element(ans.begin()+1,ans.end())<<'\n';
  51.     return;
  52. }
  53.  
  54. signed main() {
  55.     ios::sync_with_stdio(false);
  56.     cin.tie(nullptr); cout.tie(nullptr);
  57.  
  58.     int t; cin>>t;
  59.     while(t--){
  60.         solve();
  61.     }
  62. }
Runtime error #stdin #stdout 0.01s 5352KB
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Standard input is empty
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Standard output is empty
https://ideone.com/fN9WEY
language:
C++ (gcc 8.3)
created:
209 days ago
visibility:
public

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