Building Teams

input/code.cpp: In function 'void dfs(const std::vector<std::vector<int> >&, std::vector<int>&)':
input/code.cpp:25:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   25 |     for (int i = 0; i < adj.size(); i++)
      |                     ~~^~~~~~~~~~~~

#include <iostream>
#include <vector>
using namespace std;


void dfs_rec(int s, const vector<vector<int>>& adj, vector<int>& vis, int team)
{
    if (vis[s] >= 0) return;
    vis[s] = team;
    for (auto u : adj[s])
    {
        if (vis[u] == team)
        {
            cout << "IMPOSSIBLE" << endl;
            exit(0);
        }
        int newTeam;
        team == 1 ? newTeam = 0 : newTeam = 1;
        dfs_rec(u, adj, vis, newTeam);
    }
}

void dfs(const vector<vector<int>>& adj, vector<int>& vis)
{
    for (int i = 0; i < adj.size(); i++)
    {
        if (vis[i] >= 0) continue;
        else
        {
            dfs_rec(i, adj, vis, 1);
        }
    }
    return;
}

int main()
{
    int n, m;
    cin >> n >> m;
    vector<vector<int>> adj(n);
    vector<int> vis(n, -1);
    for (int i = 0; i < m; i++)
    {
        int a, b;
        cin >> a >> b;
        a--;
        b--;
        adj[a].push_back(b);
        adj[b].push_back(a);
    }
    dfs(adj, vis);
    for (int i = 0; i < n; i++)
    {
        cout << vis[i] + 1 << " ";
    }
}

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