Coloring

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

#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()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;

const int N = 2e5 + 5;

int n, m;
vector<int> adj[N];
int deg[N];
int col[N];

int main() {
    cin.tie(0)->sync_with_stdio(0);
    cin.exceptions(cin.failbit);

    cin >> n >> m;
    for (int i = 1; i <= m; i++) {
        int u, v;
        cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
        deg[u]++;
        deg[v]++;
    }

    set<pair<int, int>> st;
    for (int i = 1; i <= n; i++) {
        st.insert({deg[i], i});
    }

    while (st.size()) {
        auto it = st.end();
        it--;
        auto lst = *it;
        int u = lst.second;
        
        st.erase(it);

        vector<int> vis(7);
        for (int v : adj[u]) {
            vis[col[v]] = true;
        }

        for (int i = 1; i <= 6; i++) {
            if (!vis[i]) {
                col[u] = i;
                break;
            }
        }
        // cerr << u << ' ' << col[u] << '\n';
        assert(col[u]);

        for (int v : adj[u]) {
            if (col[v]) continue;
            st.erase({deg[v], v});
            deg[v]--;
            st.insert({deg[v], v});
        }
    }

    for (int i = 1; i <= n; i++) {
        cout << col[i] << ' ';
    }
}

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