Submission #386472

#	Time	Username	Problem	Language	Result	Execution time	Memory
386472		VROOM_VARUN	Meetings 2 (JOI21_meetings2)	C++14	100 / 100	1816 ms	42632 KiB

meetings2

/*
ID: varunra2
LANG: C++
TASK: meetings2
*/

// run centroid decomposition
// reroot
// ????
// profit

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

#ifdef DEBUG
#include "lib/debug.h"
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#define debug_arr(...) \
  cerr << "[" << #__VA_ARGS__ << "]:", debug_arr(__VA_ARGS__)
#pragma GCC diagnostic ignored "-Wsign-compare"
//#pragma GCC diagnostic ignored "-Wunused-parameter"
//#pragma GCC diagnostic ignored "-Wunused-variable"
#else
#define debug(...) 42
#endif

#define EPS 1e-9
#define IN(A, B, C) assert(B <= A && A <= C)
#define INF (int)1e9
#define MEM(a, b) memset(a, (b), sizeof(a))
#define MOD 1000000007
#define MP make_pair
#define PB push_back
#define all(cont) cont.begin(), cont.end()
#define rall(cont) cont.end(), cont.begin()
#define x first
#define y second

const double PI = acos(-1.0);
typedef long long ll;
typedef long double ld;
typedef pair<int, int> PII;
typedef map<int, int> MPII;
typedef multiset<int> MSETI;
typedef set<int> SETI;
typedef set<string> SETS;
typedef vector<int> VI;
typedef vector<PII> VII;
typedef vector<VI> VVI;
typedef vector<string> VS;

#define rep(i, a, b) for (int i = a; i < (b); ++i)
#define trav(a, x) for (auto& a : x)
#define sz(x) (int)(x).size()
typedef pair<int, int> pii;
typedef vector<int> vi;
#pragma GCC diagnostic ignored "-Wsign-compare"
// util functions

int n;
VVI adj;
VI sub;
VI out;
VI treel;
VI treer;
vector<bool> rem;
VI s;
VI cent;
VI ret;
VI par;
VI parent;
VI dist;
int tme = 0;

void init() {
  adj.resize(n);
  sub.resize(n);
  out.resize(n);
  treel.resize(n);
  treer.resize(n);
  rem.assign(n, false);
  s.assign(n, 0);
  cent.resize(n);
  ret.assign(n + 1, 0);
  par.resize(n);
  parent.resize(n);
  dist.resize(n);
}

void dfsinit(int u, int v) {
  parent[u] = v;
  treel[u] = tme++;
  sub[u] = 1;
  for (auto& x : adj[u]) {
    if (x == v) continue;
    dfsinit(x, u);
    sub[u] += sub[x];
  }
  out[u] = (n + 1) - sub[u];
  treer[u] = tme++;
}

int dfs(int n, int p = -1) {
  s[n] = 1;
  trav(x, adj[n]) {
    if (x != p and !rem[x]) {
      s[n] += dfs(x, n);
    }
  }
  return s[n];
}

int get_centroid(int n, int ms, int p = -1) {
  for (auto& x : adj[n]) {
    if (x != p and !rem[x]) {
      if (s[x] * 2 > ms) {
        return get_centroid(x, ms, n);
      }
    }
  }
  return n;
}

void centroid(int n = 0, int lvl = 0, int parr = -1) {
  int C = get_centroid(n, dfs(n));
  par[C] = parr;
  cent[C] = lvl++;
  rem[C] = true;
  for (auto& x : adj[C]) {
    if (!rem[x]) centroid(x, lvl, C);
  }
}

bool isAnc(int u, int v) {
  if (u == -1) return true;
  if (v == -1) return false;
  if (treel[u] <= treel[v] and treer[u] >= treer[v]) return true;
  return false;
}

int calc(int u, int v) {
  if (isAnc(u, v)) return (n - sub[v]);
  return sub[u];
}

void dfsdist(int u, int v, int part, int centfrom, VVI& evnts, int& cnt) {
  // we calculate distance here
  if (cent[u] <= cent[centfrom]) return;
  int val = min(calc(u, v), calc(centfrom, part));
  cnt++;
  dist[u] = dist[v] + 1;
  ret[2 * val] = max(ret[2 * val], dist[u] + 1);
  evnts.PB({calc(u, v), dist[u], part});
  for (auto& x : adj[u]) {
    if (x == v) continue;
    dfsdist(x, u, part, centfrom, evnts, cnt);
  }
}

void upd(PII nw, pair<PII, PII>& bst) {
  if (nw.y == bst.x.y) {
    bst.x = max(bst.x, nw);
  } else if (nw.y == bst.y.y) {
    bst.y = max(bst.y, nw);
    if (bst.x < bst.y) swap(bst.x, bst.y);
  } else {
    if (nw > bst.x) {
      bst.y = bst.x;
      bst.x = nw;
    } else {
      if (nw > bst.y) {
        bst.y = nw;
      }
    }
  }
}

void solve(int u) {
  // solve it for node u
  // choose a path that HAS to go through u
  // first let us calculate the sub stuff lmfao
  VVI evnts;
  dist[u] = 0;
  int cnt = 1;
  for (auto& x : adj[u]) {
    dfsdist(x, u, x, u, evnts, cnt);
  }
  // for (int i = 1; i <= cnt / 2; i++) {
  // evnts.PB({i, -1});
  // }

  // MPII there;
  // for(auto& x: evnts) {
  //   there[x[0]]++;
  // }
  // trav(x, there) {
  //   evnts.PB({x.x, -1});
  // }

  sort(all(evnts), greater<VI>());
  pair<PII, PII> bst = MP(MP(0, -1), MP(0, -2));
  for (auto& x : evnts) {
    // if (sz(x) == 3) {
    // new vertex to add
    upd(MP(x[1], x[2]), bst);
    // } else {
    if (bst.x.x == 0 or bst.y.x == 0) continue;
    int val = bst.x.x + bst.y.x + 1;
    ret[2 * x[0]] = max(ret[2 * x[0]], val);
    // debug(val, 2 * x[0], bst, u);
  }
  // }
}

int main() {
  // #ifndef ONLINE_JUDGE
  // freopen("meetings2.in", "r", stdin);
  // freopen("meetings2.out", "w", stdout);
  // #endif
  cin.sync_with_stdio(0);
  cin.tie(0);

  cin >> n;

  init();

  for (int i = 0; i < n - 1; i++) {
    int u, v;
    cin >> u >> v;
    u--, v--;
    adj[u].PB(v);
    adj[v].PB(u);
  }

  dfsinit(0, -1);

  centroid();

  for (int i = 0; i < n; i++) {
    solve(i);
  }

  int mx = 1;

  for (int i = n / 2; i >= 1; i--) {
    ret[2 * i] = max(ret[2 * i], mx);
    mx = ret[2 * i];
  }

  for (int i = 1; i <= n; i++) {
    if (i & 1)
      cout << 1 << '\n';
    else
      cout << ret[i] << '\n';
  }

  return 0;
}

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