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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. #define ll long long
  5. #define mod 1000000007
  6.  
  7. int n, m, s;
  8. vector<int> a[100005];
  9. int visited[100005];
  10. pair<int, int> cnt[100005];
  11.  
  12. void bfs( int u){
  13.     queue<int> q;
  14.     q.push(u); visited[u] = true;
  15.     cnt[u].first = 0;
  16.     while( !q.empty()){
  17.         int x = q.front(); q.pop(); 
  18.         for( int v : a[x]){
  19.             if( !visited[v]){
  20.                 q.push(v);  visited[v] = true;
  21.                 cnt[v].first = cnt[x].first + 1;
  22.             }
  23.         }
  24.     }
  25. }
  26.  
  27. void inp(){
  28.     cin >> n >> m >> s;
  29.     int u, v;
  30.     while( m--){
  31.         cin >> u >> v;
  32.         a[u].push_back(v);
  33.         a[v].push_back(u);
  34.     }
  35.  
  36.     for( int i = 1; i <= 100000; i++){
  37.         cnt[i].second = i;
  38.     }
  39.  
  40.     bfs(s);
  41.  
  42.     sort( cnt + 1, cnt + n + 1);
  43.     cout << s << " " << "0" << "\n";
  44.     for( int i = 1; i <= n; i++){
  45.         if( cnt[i].first != 0){
  46.             cout << cnt[i].second << " " << cnt[i].first << "\n";
  47.         }
  48.     }
  49.  
  50. }
  51.  
  52. int main() {
  53.     ios_base::sync_with_stdio(false);cin.tie(NULL);
  54.     // freopen("a.inp", "r", stdin);
  55.     // freopen("a.out", "w", stdout);
  56.     inp();
  57.     return 0;
  58. }
Success #stdin #stdout 0.01s 6692KB
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stdin 
Standard input is empty
stdout 
0 0
https://ideone.com/ZbTUDe
language:
C++14 (gcc 8.3)
created:
5 days ago
visibility:
public

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