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  1. #include<bits/stdc++.h>
  2.  
  3. using namespace std;
  4.  
  5. const int N = 1000005;
  6.  
  7. int n, m, Distance[N];
  8. vector<int> dsk[N];
  9. bool dd[N];
  10.  
  11. void bfs(int u) {
  12.     queue<int> Q;
  13.     Q.push(u);
  14.     Distance[u] = 0;
  15.     dd[u] = true;
  16.  
  17.     while (Q.size()) {
  18.         int u = Q.front();
  19.         Q.pop();
  20.  
  21.         /// keo u di
  22.         /// dan toi bfs() toi duoc
  23.         /// cung bi keo di
  24.         for (int v : dsk[u])
  25.             if (dd[v] == false) {
  26.                 dd[v] = true;
  27.                 Distance[v] = Distance[u] + 1;
  28.                 Q.push(v);
  29.             }
  30.     }
  31. }
  32.  
  33. int main() {
  34. //    freopen("test.inp", "r", stdin);
  35. //    freopen("test.out", "w", stdout);
  36.     int s;
  37.     cin >> n >> m >> s;
  38.     for (int i = 1; i <= m; i++) {
  39.         int u, v;
  40.         cin >> u >> v;
  41.         dsk[u].push_back(v);
  42.         dsk[v].push_back(u);
  43.     }
  44.  
  45.     bfs(s);
  46.     ///   trong so, gia tri dinh 
  47.  
  48.     /// a[i].first = a[j].first 
  49.  
  50.     /// so sanh a[i].second, a[j].second 
  51.  
  52.     vector<pair<int, int>> V;
  53.  
  54.     for (int i = 1; i <= n; i++)
  55.         if (dd[i])
  56.             V.push_back({Distance[i], i});
  57.  
  58.     sort(V.begin(), V.end());
  59.  
  60.     for (pair<int, int> v : V)
  61.         cout << v.second << " " << v.first << endl;
  62. }
  63.  
  64.  
  65.  
Success #stdin #stdout 0.01s 28196KB
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https://ideone.com/02DEUS
language:
C++14 (gcc 8.3)
created:
2 days ago
visibility:
public

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