Lexicographically minimal routes

#include <iostream>
#include <vector>
#include <algorithm>
#include <numeric>
#include <cmath>
#include <climits>
#include <iomanip>
#include <queue>
using namespace std;
vector<vector<int>> Adj;
int n, m, x, y,s , f, Trace[100001];
vector <int> ans;
queue<int> q;
void read()
{
   cin >> n >> m >> s >> f;
   Adj.resize(n + 1);
   for (int i = 1; i <= m; ++ i)
   {
       cin >> x >> y;
       Adj[x].push_back(y);
   }
   Trace[s] = -1;
   for (int i = 1; i <= n; ++ i)
   {
       sort(Adj[i].begin(), Adj[i].end());
   }
}
void DFS (int u)
{
   for (int v : Adj[u])
   {
       if (Trace[v] == 0)
       {
           Trace[v] = u;
           DFS(v);
       }
   }
}
void solve()
{
    DFS(s);
    while (f != s)
    {
        ans.push_back(f);
        f = Trace[f];
    }
    ans.push_back(s);
    reverse(ans.begin(), ans.end());
    for (int i : ans)
    {
        cout << i << ' ';
    }
}
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    read();
    solve();
}