fork download
copy 
  1. # include <iostream>
  2. # include <vector>
  3. # define pb push_back
  4. using namespace std;
  5.  
  6. vector < vector<int> > graph(10001,vector<int>());
  7. int visited[10001];
  8. int total[10001];
  9. int max1,index;
  10. void addEdge(int node1,int node2){
  11.     graph[node1].pb(node2);
  12.     graph[node2].pb(node1);
  13.     total[node1]++;
  14.     total[node2]++;
  15. }
  16. void dfs(int k,int len){
  17.     if(len>max1){
  18.         max1=len;
  19.         index=k;
  20.     }
  21.     visited[k]=1;
  22.     for(int i=0;i<graph[k].size();i++){
  23.         if(visited[graph[k][i]]==0){
  24.             dfs(graph[k][i],len+1);
  25.         }
  26.     }
  27. }
  28. int main(){
  29.     int n;
  30.     cin>>n;
  31.     for(int i=1;i<=10000;i++){
  32.         visited[i]=0;
  33.         total[i]=0;
  34.     }
  35.     max1=-1;
  36.     int u,v;
  37.     for(int i=1;i<=n;i++){
  38.         //addEdge()
  39.         cin>>u>>v;
  40.         addEdge(u,v);
  41.     }
  42.     int i;
  43.     for(i=1;i<=10000;i++){
  44.             if(total[i]==1)
  45.                 break;
  46.     }
  47.     dfs(i,0);
  48.     for(int i=1;i<=10000;i++){
  49.         visited[i]=0;
  50.         //count[i]=0;
  51.     }
  52.     int ans=max1;
  53.     max1=-1;
  54.     dfs(index,0);
  55.     if(max1>ans)
  56.         cout<<max1<<endl;
  57.     else
  58.         cout<<ans<<endl;
  59.     return 0;
  60. }
  61.  
Success #stdin #stdout 0s 3556KB
comments (?)
stdin
copy 
3
1 2
2 3
stdout
copy 
2
https://ideone.com/dUT09m
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!