Building Teams

input/code.cpp: In function 'int main(int, const char**)':
input/code.cpp:34:24: warning: comparison of integer expressions of different signedness: 'size_t' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   34 |   for (size_t i = 0; i < m; i++) {
      |                      ~~^~~
input/code.cpp:41:24: warning: comparison of integer expressions of different signedness: 'size_t' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   41 |   for (size_t i = 1; i < n + 1; i++) {
      |                      ~~^~~~~~~
input/code.cpp:47:24: warning: comparison of integer expressions of different signedness: 'size_t' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   47 |   for (size_t i = 1; i < n; i++) {
      |                      ~~^~~

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

const int N = 2e5 + 1;

vector<int> adj[N];

bool seen[N];

int result[N];

void dfs(int city, int team) {
  if (seen[city]) {
    return;
  }
  seen[city] = true;
  result[city] = 2 - team;
  for (auto i : adj[city]) {
    if (result[i] == result[city]) {
      cout << "IMPOSSIBLE" << endl;
      exit(0);
    }
    dfs(i, !team);
  }
}

int main(int argc, char const *argv[]) {
  int n, m;

  cin >> n >> m;

  for (size_t i = 0; i < m; i++) {
    int a, b;
    cin >> a >> b;
    adj[a].push_back(b);
    adj[b].push_back(a);
  }

  for (size_t i = 1; i < n + 1; i++) {
    if (!seen[i]) {
      dfs(i, 1);
    }
  }

  for (size_t i = 1; i < n; i++) {
    cout << result[i] << " ";
  }
  cout << result[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