Revise paste Untitled

#include <iostream>
#include <vector>
#include <queue>
using namespace std;
const int maxn = 100005;

vector<int> graph[maxn];
int main() {
    int n;
    cin >> n;
    
    vector<bool> visited(n + 1, false);
    for(int i = 0; i < n - 1; i++) {
        int a, b;
        cin >> a >> b;
        graph[a].push_back(b);
        graph[b].push_back(a);
    }
    queue<int> q;
    q.push(0);
    visited[0] = true;
    while(!q.empty()) {
        int node = q.front();
        q.pop();
        
        cout << node << " ";
        for(int i = 0; i < graph[node].size(); i++) {
            int neighbour = graph[node][i];
            if(!visited[neighbour]) {
                visited[neighbour] = true;
                q.push(neighbour);
            }
        }
    }
    visited[n] = true;
    q.push(n);
    vector<int> v;
    while(!q.empty()) {
        int node = q.front();
        q.pop();
        
        v.push_back(node);
        
        for(int i = 0; i < graph[node].size(); i++) {
            int neighbour = graph[node][i];
            if(!visited[neighbour]) {
                visited[neighbour] = true;
                q.push(neighbour);
            }
        }
    }
    
    for(int i = v.size() - 1; i >= 0; i--) {
        cout << v[i] << " ";
    }
    return 0;
}