Submission #1162724

#	Time	Username	Problem	Language	Result	Execution time	Memory
1162724		fryingduc	Meetings 2 (JOI21_meetings2)	C++20	100 / 100	225 ms	39700 KiB

meetings2

// centroid, not center
#include "bits/stdc++.h"

using namespace std;

#ifdef duc_debug
#include "bits/debug.h"
#else
#define debug(...)
#endif

const int maxn = 2e5 + 5;
const int LG = 19;
int n, h[maxn];
vector<int> g[maxn];
int up[maxn][LG + 1];
int sz[maxn];
int ord[maxn];
int res[maxn];

int find_centroid(int u, int prev, int n) {
  for (auto v:g[u]) {
    if (v == prev) continue;
    if (sz[v] * 2 > n) return find_centroid(v, u, n);
  }
  return u;
}

void dfs(int u, int prev) {
  sz[u] = 1;
  for (auto v:g[u]) {
    if (v == prev) continue;
    h[v] = h[u] + 1;
    up[v][0] = u;
    dfs(v, u);
    sz[u] += sz[v];
  }
}

int lca(int u, int v) {
  if (h[u] < h[v]) swap(u, v);
  for (int i = LG; i >= 0; --i) {
    if ((h[u] - h[v]) >> i & 1) {
      u = up[u][i];
    }
  }
  if (u == v) return u;
  for (int i = LG; i >= 0; --i) {
    if (up[u][i] != up[v][i]) {
      u = up[u][i], v = up[v][i];
    }
  }
  return up[v][0];
}

int dist(int u, int v) {
  return h[u] + h[v] - 2 * h[lca(u, v)];
}

void solve() {
  cin >> n;
  for (int i = 1; i < n; ++i) {
    int u, v; cin >> u >> v;
    g[u].push_back(v);
    g[v].push_back(u);
  }
  dfs(1, 0);
  int c = find_centroid(1, 0, n);
  h[c] = 0;
  up[c][0] = 0;
  dfs(c, 0);
  for (int i = 1; i <= LG; ++i) {
    for (int u = 1; u <= n; ++u) {
      up[u][i] = up[up[u][i - 1]][i - 1];
    }
  }
  iota(ord + 1, ord + n + 1, 1);
  sort(ord + 1, ord + n + 1, [](const int &x, const int &y) -> bool {
    return sz[x] > sz[y];
  });
  debug(c);
  int x = c, y = c;
  int diam = 0;
  for (int i = 2; i <= n; ++i) {
    int cur = 0;
    while (i + cur <= n and sz[ord[i]] == sz[ord[i + cur]]) {
      int u = ord[i + cur];
      vector<pair<int, int>> vec;
      vec.emplace_back(u, x);
      vec.emplace_back(u, y);
      vec.emplace_back(x, y);
      for (auto [a, b] : vec) {
        if (diam < dist(a, b)) {
          diam = dist(a, b), x = a, y = b;
        }
      }
      ++cur;
    }
    res[sz[ord[i]]] = diam;
    i = i + cur - 1;
  }
  for (int i = n; i; --i) {
    res[i] = max(res[i], res[i + 1]);
  }
  for (int i = 1; i <= n; ++i) {
    cout << (i & 1 ? 1 : 1 + res[i / 2]) << '\n';
  }
}

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

  solve();

  return 0;
}

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