DFS STL algorithom

/*
its my first dfs code so forgive me if i do wrong anything in my code...
*/

/*
Author: Fuadul Hasan(fuadul202@gmail.com)
BSMRSTU,Gopalganj
*/

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <cmath>
#include <vector>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <queue>
#include <ctime>
#include <cassert>
#include <complex>
#include <string>
#include <cstring>
#include <chrono>
#include <random>
#include <queue>
#include <bitset>
//#include<bits/stdc++.h>
using namespace std;
 
int         cinn()              {int x; scanf("%d", &x); return x;}
long long   scll()              {long long x; scanf("%lld", &x); return x;}
double      scd()               {double x; scanf("%lf", &x); return x;}
void        coutt(int x)        {printf("%d ", x);}
 
#define  scll                   scll()
#define  gcd(a,b)               __gcd(a,b)
#define  lcm(a,b)               (a*b)/gcd(a,b)
#define  PI                     acos(-1.0)
#define  vi                     std::vector<int>
#define  vll                    std::vector<ll>
#define  vit                    vector<int> :: iterator
#define  sit                    set<int> :: iterator
#define  mpsi                   std::map<string, int>
#define  pb                     push_back
#define  ll                     long long int
#define  ld                     long double
#define  ull                    unsigned long long int
#define  min3(a,b,c)            min(a,min(b,c))
#define  min4(a,b,c,d)          min(d,min(a,min(b,c)))
#define  max3(a,b,c)            max(a,max(b,c))
#define  max4(a,b,c,d)          max(d,max(a,max(b,c)))
#define  nl                     printf("\n");
#define  no                     printf("No");
#define  yes                    printf("Yes");
#define  F                      first
#define  S                      second

typedef pair<int,int> ii;
typedef std::vector<ii> vii;
 
const int mod           = 1e9 + 7;
const int inf           = (int)2e9 + 5;
const ll  Inf           = (ll)1e18 + 5;
const int N             = 1e6 + 5;
const int nn           = 4e5 + 5;


vector<vector<int>>adj;
int n;  //number of vertex
vector<bool>visited;

void dfs(int v)
{
	cout<<v<<" ";
	visited[v] = true;
	for(auto u: adj[v]){
		if(!visited[u]){
			dfs(u);
		}
	}
}

int solve()
{
	int n,e;
	cin>>n>>e;
	visited.assign(n,false);
	adj.assign(n,vector<int>());
	for(int i=0;i<e;i++){
		int a,b;
		cin>>a>>b;
		adj[a].pb(b);
	}
	for(int i=1;i<n;i++){
		if(!(visited[i])){
			dfs(i);
		}
	}
}

int main()
{
    int test = 1, tc = 0;
    //scanf("%d", &test);
   // (void)getchar();
    //cin >> test;
    while (test--) {
        //printf("Case %d: ", ++tc);
        solve();
    }
 
    return 0;
}