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  1. #include<bits/stdc++.h>
  2. #define MAX 300001
  3. #define INF 1e9
  4.  
  5. using namespace std;
  6.  
  7. vector<int>adj[MAX];
  8. vector<int>city;
  9. int dis[MAX], k;
  10.  
  11. void dij(int i){
  12. 	fill(dis, dis+MAX, INF);
  13. 	queue<int>q;
  14. 	q.push(i);
  15. 	dis[i]=0;
  16.  
  17. 	while(!q.empty()){
  18. 		int x=q.front();
  19. 		q.pop();
  20.  
  21. 		for(int i=0;i<adj[x].size();i++){
  22. 			int nx=adj[x][i];
  23. 			if(dis[nx]>dis[x]+1){
  24. 				dis[nx]=dis[x]+1;
  25. 				q.push(nx);
  26. 			}
  27. 		}
  28. 	}
  29. }
  30.  
  31. int main(){
  32. 	ios_base::sync_with_stdio(NULL);
  33. 	cin.tie(0),cout.tie(0);
  34.  
  35. 	int n,m,x,a,b,cnt=0;
  36.  
  37. 	cin>>n>>m>>k>>x;
  38.  
  39. 	while(m--){
  40. 		cin>>a>>b;
  41.  
  42. 		adj[a].push_back(b);
  43. 	}
  44.  
  45. 	dij(x);
  46.  
  47. 	for(int i=1;i<=n;i++){
  48. 		if(dis[i]==k)
  49. 			city.push_back(i);
  50. 	}
  51.  
  52. 	sort(city.begin(), city.end());
  53.  
  54. 	if(city.empty())
  55. 		cout<<-1;
  56. 	else
  57. 		for(int i : city){
  58. 			cout<<i<<'\n';
  59. 		}
  60.  
  61. 	return 0;
  62. }
Success #stdin #stdout 0.01s 11704KB
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https://ideone.com/PfJ3eq
language:
C++ (gcc 8.3)
created:
4 hours ago
visibility:
public

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