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  1. #include<bits/stdc++.h>
  2. using namespace std;
  3. typedef long long int ll;
  4. int main()
  5. {
  6.     ll n,m,k,i;
  7.     cin>>n>>m>>k;
  8.     set< ll > A[n+1];
  9.     for(i=0;i<m;i++)
  10.     {
  11.         ll u,v;
  12.         cin>>u>>v;
  13.         A[u].insert(v);
  14.         A[v].insert(u);
  15.     }
  16.     ll visited[n+1];
  17.     for(i=1;i<=n;i++)
  18.     {
  19.         visited[i]=-1;
  20.     }
  21.     queue< pair< ll,ll > > q;
  22.     for(i=0;i<k;i++)
  23.     {
  24.         ll r;
  25.         cin>>r;
  26.         q.push({r,0});
  27.         visited[r]=0;
  28.     }
  29.     ll ans=-1;
  30.     bool flag=false;
  31.     while(!q.empty())
  32.     {
  33.         pair< ll,ll > m=q.front();
  34.         q.pop();
  35.         ans=m.second;
  36.         for(auto it: A[m.first])
  37.         {
  38.             if(visited[it]==-1)
  39.             {
  40.                 q.push({it,m.second+1});
  41.                 visited[it]=m.second+1;
  42.                 A[it].erase(m.first);
  43.             }
  44.             else
  45.             {
  46.                 ans=m.second;
  47.                 flag=true;
  48.                 break;
  49.             }
  50.         }
  51.         if(flag)
  52.         {
  53.             break;
  54.         }
  55.     }
  56.     ll sol=0;
  57.     for(i=1;i<=n;i++)
  58.     {
  59.         if(visited[i]>=0&&visited[i]<=ans)
  60.         {
  61.             sol++;
  62.         }
  63.     }
  64.     cout<<sol<<endl;
  65.     return 0;
  66. }
Success #stdin #stdout 0s 15240KB
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https://ideone.com/CCjqq6
language:
C++14 (gcc 8.3)
created:
6 years ago
visibility:
public

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