Building Teams

#include<iostream>
#include<vector>
 
 
using namespace std;
 
vector<int> team;
vector<vector<int>> adj;
vector<bool> vis;
bool dfs(int node, int ct)
{
    vis[node] = 1;
    team[node] = ct;
    for (auto &i : adj[node])
    {
        if (team[i] == 0)
        {
            bool temp = dfs(i, 3 - ct);
            if (not temp)
                return false;
        }
        else if (team[i] == ct)
        {
            return false;
        }
    }
    return true;
}
 
int main(){
    int n,m;
    cin >> n >> m;
    team = vector<int> (n + 1);
    adj = vector<vector<int>> (n+1);
    vis = vector<bool> (n+1);
    for(int i = 0; i < m; ++i){
        int a,b;
        cin >> a >> b;
        adj[a].push_back(b);
        adj[b].push_back(a);
    }
    bool b = true;
    for (int i = 1; i <= n; i++)
        {
            if (vis[i])
                continue;
            int res = dfs(i, 1);
            if (!res)
            {
                b = false;
                break;
            }
        }
        if (b)
        {
            for (int i = 1; i <= n; i++)
                cout << team[i] << " ";
        }
        else
            cout << "IMPOSSIBLE\n";
}

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