1106D- Lunar New Year and a Wander.cpp

#include<bits/stdc++.h>
using namespace std;


//{
#define si(a) scanf("%d",&a)
#define sii(a,b) scanf("%d %d",&a,&b);
#define siii(a,b,c) scanf("%d %d %d",&a,&b,&c);

#define sl(a) scanf("%lld",&a)
#define sll(a,b) scanf("%lld %lld",&a,&b);
#define slll(a,b,c) scanf("%lld %lld %lld",&a,&b,&c);

#define outi(a) printf("%d\n",a)
#define outii(a,b) printf("%d %d\n",a,b)
#define outis(a) printf(" %d",a)

#define outl(a) printf("%lld\n",a)
#define outll(a,b) printf("%lld %lld\n",a,b)
#define outls(a) printf(" %lld",a)

#define cel(n,k) ((n-1)/k+1)
#define sets(a) memset(a, -1, sizeof(a))
#define clr(a) memset(a, 0, sizeof(a))
#define max(a,b) ((a)>(b)? (a):(b))
#define min(a,b) ((a)<(b)? (a):(b))
#define fr(n) for(int i=0;i<n;i++)
#define fr1(n) for(int i=1;i<=n;i++)
#define pb push_back
#define all(v) v.begin(),v.end()
#define mp make_pair
#define ff first
#define ss second
#define INF 10000007
#define fastIO() ios_base::sync_with_stdio(false); cin.tie(NULL);

typedef long long i64;
typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef pair<long long,long long> pll;
//}

const int maxn= 1e5+5;

vector<int> v[maxn];
int n, vis[maxn], level[maxn], edges, parent[maxn];

void reset(){
    clr(vis);
    clr(level);
    sets(parent);
}

void bfs(int source){
    set<int> q;
    q.insert(source);
    vis[source]= 1;

    while(!q.empty()){
        int u= *q.begin();
        printf("%d ",u);

        q.erase(q.begin());

        fr(v[u].size()){
            int node= v[u][i];

            if(!vis[node]){
                vis[node]= 1;

                q.insert(node);
            }

        }

    }

}

main(){
    reset();
    int a, b;

    sii(n,edges);

    fr1(edges){
        sii(a,b);

        v[a].pb(b);
        v[b].pb(a);
    }


    bfs(1);
}