50分求救

#include <vector>
#include <algorithm>
#include <cstring>
using namespace std;

const int MAXN = 10005;
vector<int> G[MAXN];
int n, m;
int color[MAXN];
bool used[MAXN];

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    
    cin >> n >> m;
    for (int i = 0; i < m; i++) {
        int u, v;
        cin >> u >> v;
        G[u].push_back(v);
        G[v].push_back(u);
    }
    
    int max_degree = 0;
    for (int i = 1; i <= n; i++) {
        sort(G[i].begin(), G[i].end());
        max_degree = max(max_degree, (int)G[i].size());
    }
    
    vector<int> order(n);
    for (int i = 0; i < n; i++) order[i] = i + 1;
    
    sort(order.begin(), order.end(), [&](int a, int b) {
        return G[a].size() > G[b].size();
    });
    
    int ans = 0;
    for (int i = 0; i < n; i++) {
        int u = order[i];
        memset(used, 0, sizeof(used));
        
        for (int v : G[u]) {
            if (color[v] != 0) {
                used[color[v]] = true;
            }
        }
        
        int c = 1;
        while (used[c]) c++;
        color[u] = c;
        ans = max(ans, c);
    }
    
    cout << ans << endl;
    return 0;
}