Submission #869870

#	Time	Username	Problem	Language	Result	Execution time	Memory
869870		garam1732	Meetings 2 (JOI21_meetings2)	C++14	100 / 100	716 ms	42628 KiB

meetings2

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

#define ff first
#define ss second
#define bl " "
#define endl "\n"
#define all(v) v.begin(), v.end()
#define comp(v) v.erase(unique(all(v)), v.end())
typedef long long ll;
typedef pair<int, int> pi;
typedef pair<pi, int> pii;
typedef pair<ll, ll> pll;

const int MAXN = 200200;
const int MOD = 998244353;

vector<int> adj[MAXN];
priority_queue<pi> pq[MAXN], q;
set<pi> st;

bool vst[MAXN];
int res[MAXN], num[MAXN], tmp[MAXN];
int dst[MAXN], cnt[MAXN];

void dfs1(int here, int par) {
    cnt[here] = 1;

    if(vst[here]) return;
    for(int there : adj[here]) {
        if(there == par) continue;

        dfs1(there, here);
        cnt[here] += cnt[there];
    }
}

void dfs2(int here, int par, int t) {
    if(!vst[here]) {
        for(int there : adj[here]) {
            if(there == par) continue;

            dst[there] = dst[here] + 1;
            dfs2(there, here, t);
        }
    }

    int x = (num[here] < num[par] ? num[here] : num[1]-num[par]);
    pq[t].push(pi(x, dst[here]));
}

void solve(int here) {
    dfs1(here, here);

    int n = cnt[here];
    for(int par = here; ; ) {
        bool flag = true;
        for(int there : adj[here]) {
            if(there == par || vst[there]) continue;
            if(cnt[there]*2 > n) {
                flag = false;
                par = here; here = there;
                break;
            }
        }

        if(flag) break;
    }

    dst[here] = 0; int t = 0;
    for(int there : adj[here]) {
        while(pq[t].size()) pq[t].pop();
        dst[there] = dst[here] + 1;
        dfs2(there, here, t);

        tmp[t] = 0;
        t++;
    }

    if(t == 0) return;

    while(q.size()) q.pop();
    for(int i = 0; i < t; i++) q.push(pi(pq[i].top().ff, i));

    st.clear();
    int mx = q.top().ff;
    while(q.size()) {
        while(q.size() && q.top().ff == mx) {
            pi x = q.top(); q.pop();
            if(st.find(pi(tmp[x.ss], x.ss)) != st.end()) st.erase(pi(tmp[x.ss], x.ss));
            tmp[x.ss] = max(tmp[x.ss], pq[x.ss].top().ss);
            st.insert(pi(tmp[x.ss], x.ss));
            pq[x.ss].pop();
            if(pq[x.ss].size()) q.push(pi(pq[x.ss].top().ff, x.ss));
        }

        //cout<<mx<<bl<<it->ff<<bl<<next(it)->ff<<endl;
        if(st.size() > 1) {
            auto it = prev(st.end());
            res[mx] = max(res[mx], it->ff+prev(it)->ff+1);
        }
        if(q.size()) mx = q.top().ff;
    }

    vst[here] = 1;
    for(int there : adj[here]) {
        if(!vst[there])
            solve(there);
    }
}

int main() {
    ios_base::sync_with_stdio(0); cin.tie(0);

    int n; cin >> n;
    for(int i = 1; i < n; i++) {
        int a, b; cin >> a >> b;
        adj[a].push_back(b);
        adj[b].push_back(a);
    }

    dfs1(1, 1);

    for(int i = 1; i <= n; i++) num[i] = cnt[i];

    int idx = 0;
    for(int i = 2; i <= n; i++)
        idx = max(idx, min(cnt[i], n-cnt[i]));

    res[n] = 1; res[idx] = 2;

    solve(1);

    for(int i = n-1; i; i--) res[i] = max(res[i], res[i+1]);
    for(int i = 1; i <= n; i++) cout << (i%2 ? 1 : res[i/2]) << endl;
}

• Subtask 1: 4 / 4
• Subtask 2: 16 / 16
• Subtask 3: 80 / 80