Pubg

#include<bits/stdc++.h> #define v(x) vector #define pb(x) push_back(x) #define fori0(i,n) for(int i=0;i<n;i++) #define in(n) int n;cin>>n using namespace std; const int MAX=1e5+2; v(int) tree[MAX]; bool vis[MAX]; int start,curlength=0; void dfs(int s,int len){ vis[s]=true; if(len>curlength) {start=s;curlength=len;} for(auto i:tree[s]) vis[s]=true; if(len>curlength) {start=s;curlength=len;} for(auto i:tree[s]) if(!vis[i]) dfs(i,len+1); } int main() { ios_base::sync_with_stdio(false);cin.tie(NULL); in(n); fori0(i,n){ in(x);in(y); tree[x].pb(y);tree[y].pb(x); } dfs(1,1); cout<<start<<" "; memset(vis,false,n); curlength=0; dfs(start,1); cout<<start; return 0; }