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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. int main() {
  5. 	int n, m;
  6. 	cin>>n>>m;
  7. 	vector<int> adjList[n];
  8. 	for(int i=0;i<m;i++){
  9. 		int x,y;
  10. 		cin>>x>>y;
  11. 		adjList[x].push_back(y);
  12. 		adjList[y].push_back(x);
  13. 	}
  14.  
  15. 	int source=1;
  16. 	vector<int> visited(n, 0);
  17. 	vector<int> level(n, 0);
  18. 	vector<int> ways(n, 0);
  19. 	queue<int> q;
  20. 	q.push(source);
  21. 	visited[source]=1;
  22. 	ways[source]=1;
  23. 	while(!q.empty()){
  24. 		int node=q.front();
  25. 		q.pop();
  26. 		visited[node]=1;
  27. 		for(auto adjNode : adjList[node]){
  28. 			if(!visited[adjNode]){
  29. 				//first time visit
  30. 				visited[adjNode]=1;
  31. 				level[adjNode]=level[node]+1;
  32. 				ways[adjNode]=ways[node];
  33. 				q.push(adjNode);
  34. 			}
  35. 			else{
  36. 				if(level[adjNode]==level[node]+1){
  37. 					//node adjNode is on shortest path
  38. 					ways[adjNode]=ways[adjNode]+ways[node];
  39. 				}
  40. 				else{
  41. 					//node adjNode is not on the shortest path
  42. 					//no need to count
  43. 				}
  44. 			}
  45. 		}
  46. 	}
  47. 	for(int i=0;i<ways.size();i++){
  48. 		cout<<"node "<<i<<" : "<<ways[i];
  49. 		cout<<"\n";
  50. 	}
  51. 	return 0;
  52. }
  53.  
Success #stdin #stdout 0s 5296KB
comments (?)
stdin
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5 5
1 2
1 3
2 4
3 4
4 0
stdout
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node 0 : 2
node 1 : 1
node 2 : 1
node 3 : 1
node 4 : 2
https://ideone.com/C6gQ5s
language:
C++ (gcc 8.3)
created:
6 hours ago
visibility:
public

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