Building Teams

// ~/.vim/cpp_template.cpp
#include <bits/stdc++.h>
#include <iostream>
#include <vector>
#include <algorithm>

#define REP(i,a,b) for (int i = a; i < b; i++)


using namespace std;


void dfs(int s, vector<int> *visited, vector<int> (*adj)[]) {
    // process node s

    for (auto u: (*adj)[s]) {
        if((*visited)[u] != 0 && (*visited)[s] == (*visited)[u]){
            cout << "IMPOSSIBLE" << endl;
            exit(0);
        }
        if((*visited)[u] != 0) continue;
        if((*visited)[s] == 1){
            (*visited)[u] = 2;
        }else{
            (*visited)[u] = 1;
        }
        dfs(u, visited, adj);
    }
}
/*
vector<int> adj[N];                                                          
vector<bool> visited(N, false);
int u, v;
for(int i = 0; i < M;i++){
    cin >> u >> v;
    u--;
    v--;
    adj[u].push_back(v);
    adj[v].push_back(u);
}
*/

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    // Your code starts here

    int N, M;
    cin >> N >> M;


    vector<int> adj[N];                                                          
    vector<int> visited(N, 0);
    int u, v;
    for(int i = 0; i < M;i++){
        cin >> u >> v;
        u--;
        v--;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }

    REP(i, 0, N){
        if(visited[i] == 0){
            visited[i] = 1;
        }else continue;
        dfs(i, &visited, &adj);
    }

    REP(i, 0, N){
        cout << visited[i] << ' ';
    }
    cout << endl;
    
    
    return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED