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  1. #include <stdio.h>
  2. #include <queue>
  3. #include <vector>
  4. using namespace std;
  5.  
  6. queue<pair<int, int>> q;
  7. vector<pair<int, int>> way[300005];
  8. int v[300005];
  9. int res[300005];
  10.  
  11. int main(){
  12.     int n, k, d;
  13.     scanf("%d%d%d", &n, &k, &d);
  14.     for(int i=0; i<k; i++){
  15.         int p;
  16.         scanf("%d", &p);
  17.         q.push({p, 0});
  18.     }
  19.     for(int i=0; i<n-1; i++){
  20.         int u, v;
  21.         scanf("%d%d", &u, &v);
  22.         way[u].push_back({v, i+1});
  23.         way[v].push_back({u, i+1});
  24.     }
  25.     while(!q.empty()){
  26.         int pos = q.front().first;
  27.         int from = q.front().second;
  28.         q.pop();
  29.         if(v[pos]) continue;
  30.         v[pos] = 1;
  31.         for(int i=0; i<way[pos].size(); i++) if(way[pos][i].first != from){
  32.             if(v[way[pos][i].first]) res[way[pos][i].second] = 1;
  33.             else q.push({way[pos][i].first, pos});
  34.         }
  35.     }
  36.     int rescnt=0;
  37.     for(int i=1; i<=n-1; i++) if(res[i]) rescnt++;
  38.     printf("%d\n", rescnt);
  39.     for(int i=1; i<=n-1; i++) if(res[i]) printf("%d ", i);
  40.     return 0;
  41. }
Success #stdin #stdout 0.01s 25360KB
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https://ideone.com/nlPVW0
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
secret

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