29C - Mail Stamps - CodeForces Solution

#include <bits/stdc++.h>
#define ll long long
using namespace std;
const int N = 1e5+5;
const int MOD = 1e9+7;
int edge,c,n,m,sum=0,flag,x,srcx,srcy;
//vector<int>adj[N];
priority_queue<int>pq;
map<ll,ll>visited;
int dx[]={0,0,1,-1};
int dy[]={1,-1,0,0};
bool valid(int i,int j){
 return (i < n && i >= 0 && j < m && j >= 0);
}
map<int,vector<int>>adj;
void dfs(int node){
    cout<<node<<" ";
    visited[node]=1;
    for(auto adjnode:adj[node]){
       if(!visited[adjnode]){
            dfs(adjnode);

    }
    }

}
int main(){
    cin>>n;
    for(int i=0;i<n;i++){
        int x,y;
        cin>>x>>y;
        adj[x].push_back(y);
        adj[y].push_back(x);

    }
    for(auto x:adj){
        if(x.second.size()==1){
            dfs(x.first);
            break;
        }
    }
    //dfs(1);
    return 0;
}