Endpoints of a Diameter

vector<int> solve(int N, vector<vector<int> > edge) {
    int deg[N + 1];
    memset(deg, 0, sizeof(deg));
    int alive = N;
    vector<vector<int> > ed(N + 1);
    queue<int> q;
    for(int i = 0; i < N - 1; i++) {
        int a = edge[i][0], b = edge[i][1];
        ed[a].push_back(b);
        ed[b].push_back(a);
        deg[a]++;
        deg[b]++;
    }
    for(int i = 1; i <= N; i++)
        if(deg[i] == 1)
            q.push(i);
    while(alive > 2) {
        queue<int> next;
        while(!q.empty()) {
            int now = q.front();
            assert(deg[now] == 1);
            q.pop();
            deg[now] = -1;
            alive--;
            for(int i = 0; i < ed[now].size(); i++) {
                    deg[ed[now][i]]--;
                    if(deg[ed[now][i]] == 1)
                        next.push(ed[now][i]);
            }
        }
        q = next;
    }
    vector<int> sus;
    for(int i = 1; i <= N; i++)
        if(deg[i] > -1)
            sus.push_back(i);
    assert(sus.size() == alive);
    vector<int> ans(N, 0);
    for(int i = 0; i < alive; i++) {
        int st = sus[i];
        queue<int> bfs;
        int dis[N + 1];
        memset(dis, -1, sizeof(dis));
        dis[st] = 0;
        bfs.push(st);
        int mx = 0;
        while(!bfs.empty()) {
            int now = bfs.front();
            bfs.pop();
            mx = max(dis[now], mx);
            for(int i = 0; i < ed[now].size(); i++) {
                if(dis[ed[now][i]] > -1) continue;
                dis[ed[now][i]] = dis[now] + 1;
                bfs.push(ed[now][i]);
            }
        }
        for(int i = 1; i <= N; i++)
            if(dis[i] == mx)
                ans[i - 1] = 1;
    }
    return ans;
}