bfs

#include<iostream>
#include<algorithm>
#include<queue>
#include<vector>
#include<map>
using namespace std;


map<int, bool> isFree;
vector<vector<int>> adjMatrix;

void BFS(int start) {
    queue<int> que;

    isFree[start] = false;
    que.push(start);


        for (size_t i = 0; i < adjMatrix.size(); i++)
        {
            for (size_t j = 0; j < adjMatrix[i].size(); j++)
            {

                if (isFree[adjMatrix[i][j]]) {

                    que.push(adjMatrix[i][j]);
                    isFree[adjMatrix[i][j]] = false;

                }

            }

        }

        while (!que.empty()) {

            start = que.front();
            cout << start+1 << " ";
            que.pop();

        }



}
int main() {

    int N, V;
    cin >> N >> V;


    for (size_t i = 0; i < N; i++)
    {
        isFree.insert(make_pair(i,true));
    }
    adjMatrix.resize(N);

    int a, b;
    for (size_t i = 0; i < V; i++)
    {
        cin >> a >> b;
        adjMatrix[a-1].push_back(b-1);
        adjMatrix[b-1].push_back(a-1);
    }
    for (size_t i = 0; i < adjMatrix.size(); i++)
    {
        for (size_t j = 0; j < adjMatrix[i].size(); j++)
        {
            cout << adjMatrix[i][j]+1 << " ";
        }
        cout << endl;
    }
    BFS(2);

}