Submission #1098253

#	Time	Username	Problem	Language	Result	Execution time	Memory
1098253		onbert	Meetings 2 (JOI21_meetings2)	C++17	20 / 100	1188 ms	1628 KiB

meetings2

#include <bits/stdc++.h>
using namespace std;
#define int long long
const int maxn = 4005, lg = 20;
int n;
vector<int> adj[maxn];

int lift[maxn][lg];
int d[maxn], sz[maxn];
void dfs(int u) {
    sz[u] = 1;
    for (int i=1;i<lg;i++) {
        if (lift[u][i-1]==-1 || lift[lift[u][i-1]][i-1]==-1) break;
        lift[u][i] = lift[lift[u][i-1]][i-1];
    }
    for (int v:adj[u]) {
        adj[v].erase(find(adj[v].begin(), adj[v].end(), u));
        lift[v][0] = u;
        d[v] = d[u] + 1;
        dfs(v);
        sz[u] += sz[v];
    }
}

int lca(int u, int v) {
    if (d[u] > d[v]) swap(u, v);
    for (int i=lg-1;i>=0;i--) {
        if (d[v] - (1<<i) >= d[u]) v = lift[v][i];
    }
    if (u==v) return u;
    for (int i=lg-1;i>=0;i--) if (lift[u][i]!=lift[v][i]) {
        u = lift[u][i], v = lift[v][i];
    }
    return lift[u][0];
}

int lift2(int u, int D) {
    for (int i=lg-1;i>=0;i--) {
        if (d[u] - (1<<i) >= D) u = lift[u][i];
    }
    return u;
}

signed main() {
    ios::sync_with_stdio(0); cin.tie(0);
    cin >> n;
    for (int i=1;i<=n-1;i++) {
        int u, v;
        cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    for (int i=1;i<=n;i++) for (int j=0;j<lg;j++) lift[i][j] = -1;
    d[1] = 0;
    dfs(1);
    int ans[n/2+1];
    for (int i=1;i<=n/2;i++) ans[i] = 1;
    for (int i=1;i<=n;i++) for (int j=i+1;j<=n;j++) {
        int m = lca(i, j);
        int a = sz[i], b = sz[j];
        if (m==i) {
            int thing = lift2(j, d[i]+1);
            a = n - sz[thing];
        }
        if (m==j) {
            int thing = lift2(i, d[j]+1);
            b = n - sz[thing];
        }
        int dist = d[i] + d[j] - d[m] * 2;
        // cout << i << " " << j << " " << dist << endl;
        // cout << a << " " << b << endl;
        ans[min(a, b)] = max(dist + 1, ans[min(a, b)]);
    }
    for (int i=n/2-1;i>=1;i--) ans[i] = max(ans[i], ans[i+1]);
    for (int i=1;i<=n;i++) {
        if (i%2==0) cout << ans[i/2] << endl;
        else cout << "1\n";
    }
}

• Subtask 1: 4 / 4
• Subtask 2: 16 / 16
• Subtask 3: 0 / 80