Building Teams

#include <bits/stdc++.h> 
using namespace std;
#define REP(i,a,b) for (int i = a; i < b; i++)

int main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    int n;
    int m;
    cin>>n>>m;
    bool impossible = false;

    vector<int> adj[n];
    REP(i,0,m){
        int a;
        int b;
        cin>>a>>b;
        a--;b--;
        adj[a].push_back(b);
        adj[b].push_back(a);
    }


    queue<int> q;
    bool visited[n];
    bool distance[n]; 

    REP(i,0,n){
    if (!visited[i])
    {
    visited[i] = true;
    distance[i] = false;
    q.push(i);
    while (!q.empty()) {
        int s = q.front(); q.pop();
        // process node s
        for (auto u : adj[s]) {
            if (visited[u]) {
                if (distance[u]==distance[s]){
                    impossible= true;
                }
                continue;
            }
            visited[u] = true;
            distance[u] = !distance[s];
            q.push(u);
        }
        }
    }}

    if (impossible){
        cout<<"IMPOSSIBLE";
    }
    else{
    
    REP(i,0,n-1){
        if (distance[i]){
            cout<<1<<" ";
        }
        else{
            cout<<2<<" ";
        }
    }
    if (distance[n-1]){
            cout<<1;
        }
        else{
            cout<<2;
        }
}
    return 0;
}

Test 1

Verdict: WRONG ANSWER

Test 2

Verdict: WRONG ANSWER

Test 3

Verdict: WRONG ANSWER

Test 4

Verdict: WRONG ANSWER

Test 5

Verdict: ACCEPTED

Test 6

Verdict: WRONG ANSWER

Test 7

Verdict: WRONG ANSWER

Test 8

Verdict: WRONG ANSWER

Test 9

Verdict: WRONG ANSWER

Test 10

Verdict: ACCEPTED

Test 11

Verdict: WRONG ANSWER

Test 12

Verdict: WRONG ANSWER