Submission #1262525

#	Time	Username	Problem	Language	Result	Execution time	Memory
1262525		madamadam3	Migrations (IOI25_migrations)	C++20	72.89 / 100	47 ms	1720 KiB

migrations

#include "migrations.h"
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
using pi = pair<int, int>;
using vi = vector<int>;
using vvi = vector<vi>;

void dfs(int u, int p, vi &dist, vvi &adj) {
  for (auto &v : adj[u]) {
    if (v == p) continue;
    dist[v] = dist[u] + 1;
    dfs(v, u, dist, adj);
  }
}

int furthest_from(int u, int n, vvi &adj) {
  vector<int> dist(n);
  dfs(u, u, dist, adj);

  int f = 0; for (int i = 0; i < n; i++) if (dist[i] > dist[f]) f = i;
  return f;
}

int dist_between(int n, int u, int v, vvi &adj) {
  vector<int> dist(n);
  dfs(u, u, dist, adj);

  return dist[v];
}

pi furthest_pair(int n, vvi &adj) {
  vector<int> dist(n);
  dfs(0, 0, dist, adj);
  int f1 = 0; for (int i = 0; i < n; i++) if (dist[i] > dist[f1]) f1 = i;
  dist = vi(n, 0);
  dfs(f1, f1, dist, adj);
  int f2 = 0; for (int i = 0; i < n; i++) if (dist[i] > dist[f2]) f2 = i;

  return {min(f1, f2), max(f1, f2)};
}

vi to_base(ll A, ll b, int pad = 0) {
  vi ans;
  while (A > 0LL) {
    ans.push_back(A % b);
    A /= b;
  }
  
  while (ans.size() < pad) ans.push_back(0);
  return ans;
}

ll from_base(vi bx, ll b) {
  ll po = 1;
  ll ans = 0;

  for (auto &el : bx) {
    ans += ll(el) * po;
    po *= b;
  }

  return ans;
}

vvi adj;
pi fr;
int diam = 0,  prev_change = 0, cpos = 0;
bool used2 = false;
vector<int> change_types;

int x = 0, actual_step = 0;
int send_message(int n, int i, int Pi) {
  if (i <= 1) adj.assign(n+1, vi());
  x = n - 28;

  adj[Pi].push_back(i);
  adj[i].push_back(Pi);

  if (i < x) return 0;
  int step = actual_step++;

  if (step == 0) {fr = furthest_pair(n, adj); diam = dist_between(n, fr.first, fr.second, adj); prev_change = fr.first;}

  pi cfr = furthest_pair(n, adj);
  int u = cfr.first, v = cfr.second;
  int cdiam = dist_between(n, u, v, adj);

  int type = cdiam == diam ? 0 : (dist_between(n, i, prev_change, adj) == cdiam ? 2 : 1);
  diam = cdiam; prev_change = type == 0 ? prev_change : i;

  int ans = step < 14 ? min(1, fr.first & (1 << step)) : min(1, fr.second & (1 << (step - 14)));
  if (step >= 14 && used2) ans = 0;

  if (type == 0) {
    return ans;
  } else if (type == 1) {
    return ans + 2;
  } else {
    used2 = true; actual_step--; 
    return 4;
  }
}

// 0 - no change, 1 - cur replaces prev, 2 - cur connects to prev
pi longest_path(vi S) {
  int n = S.size();
  int x = n - 28;

  int u = 0, v = 0;
  vector<pi> switches; // idx, 0 if extension, 1 if connection

  int step = 0;
  for (int i = x; i < n; i++) {
    if (S[i] == 4) {
      switches.push_back({i, 1});
      continue;
    }

    int value = S[i];
    if (S[i] >= 2) {
      switches.push_back({i, 0});
      value -= 2;
    }
    
    if (step < 14) u |= value << step;
    else v |= value << (step - 14);

    step++;
  }

  int A = u, B = v;
  int L = u; 

  for (auto &el : switches) {
    int w = el.first;
    if (el.second) { // joining
      (L == A ? B : A) = w;
    } else { // extending
      (L == A ? A : B) = w;
    }
    L = w; 
  }

  return {A, B}; 
}

• Subtask 0: 0 / 0
• Subtask 1: 30 / 30
• Subtask 2: 42.8897 / 70