Coloring

In file included from /usr/include/c++/11/cassert:44,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:33,
                 from input/code.cpp:1:
input/code.cpp: In function 'int main()':
input/code.cpp:54:23: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   54 |     assert(ord.size() == n);
      |            ~~~~~~~~~~~^~~~

#include <bits/stdc++.h>
using namespace std;

#ifdef LOCAL
#define D(x) {x;}
#else
#define D(x)
#endif
#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define all(x) begin(x),end(x)
#define sz(x) (int) (x).size()
using ll = long long;
using pii = pair<int, int>;
using vi = vector<int>;

int main() {
    cin.tie(0) -> sync_with_stdio(0);
    cin.exceptions(cin.failbit);
    int n, m;
    cin >> n >> m;
    int deg[n] {};
    vector<int> v[n];
    for (int i = 0; i < m; ++i) {
        int a, b;
        cin >> a >> b;
        a--; b--;
        deg[a]++;
        deg[b]++;
        v[a].push_back(b);
        v[b].push_back(a);
    }
    priority_queue<pair<int, int>> q;
    for (int i = 0; i < n; ++i) {
        q.push({-deg[i], i});
    }
    int z[n] {};
    vector<int> ord;
    while (q.size()) {
        auto [x, i] = q.top();
        q.pop();
        if (z[i]) continue;
        if (deg[i] >= 6) {
            while (true);
        }
        z[i] = 1;
        ord.push_back(i);
        for (auto j : v[i]) {
            if (z[j]) continue;
            deg[j]--;
            q.push({-deg[j], j});
        }
    }
    int col[n] {};
    assert(ord.size() == n);
    for (int oi = n-1; oi >= 0; --oi) {
        int i = ord[oi];
        D(cout << i << " ";)
        int cz[7] {};
        for (int j : v[i]) {
            cz[col[j]] = 1;
        }
        for (int c = 1; c <= 6; ++c) {
            if (!cz[c]) {
                col[i] = c;
                break;
            }
        }
    }
    D(cout << endl;)
    for (int i = 0; i < n; ++i) {
        cout << col[i] << " ";
    }
    cout << endl;
}

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

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED

Test 22

Verdict: ACCEPTED

Test 23

Verdict: ACCEPTED

Test 24

Verdict: ACCEPTED

Test 25

Verdict: ACCEPTED

Test 26

Verdict: ACCEPTED

Test 27

Verdict: ACCEPTED