제출 #1286389

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1286389		kawhiet	세계 지도 (IOI25_worldmap)	C++20	22 / 100	31 ms	4364 KiB

worldmap

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

int node;

vector<bool> vis;
vector<int> par, k;
vector<set<int>> t, g;
vector<vector<int>> adj;

// g - spanning tree
// t - not included in spanning tree
// adj - all

struct DSU {
  int n;
  vector<int> p;

  // DSU(int sz) {
  //   n = sz;
  //   p.resize(n, -1);
  // }

  int root(int x) {
    if (p[x] == -1) {
      return x;
    }
    return p[x] = root(p[x]);
  }

  bool link(int u, int v) {
    u = root(u);
    v = root(v);
    if (u == v) {
      return false;
    }
    p[u] = v;
    return true;
  }
};

DSU dsu;
vector<int> d, from;

void get_dist(int u, vector<bool> &vis) {
  vis[u] = 1;
  for (auto v : adj[u]) {
    if (!vis[v]) {
      d[v] = d[u] + 1;
      from[v] = u;
      get_dist(v, vis);
    }
  }
}

pair<int, int> longest_path(int n) {
  d.assign(n + 1, 0);
  from.assign(n + 1, -1);
  vector<bool> vis(n + 1);
  get_dist(1, vis);
  int u = max_element(d.begin(), d.end()) - d.begin();
  fill(d.begin(), d.end(), 0);
  fill(vis.begin(), vis.end(), 0);
  get_dist(u, vis);
  int v = max_element(d.begin(), d.end()) - d.begin();
  int x = v;
  while (from[x] != u) {
    dsu.link(x, from[x]);
    g[x].insert(from[x]);
    g[from[x]].insert(x);
    x = from[x];
  }
  if (u != x) {
    dsu.link(u, x);
    g[u].insert(x);
    g[x].insert(u);
  }
  return {u, v};
}

void dfs(int u) {
  vis[u] = 1;
  k.push_back(u);
  bool has = 0;
  for (auto v : g[u]) {
    if (v == node) {
      has = 1;
      continue;
    }
    if (!vis[v]) {
      par[v] = u;
      dfs(v);
    }
  }
  if (has) {
    if (!vis[node]) {
      par[node] = u;
      dfs(node);
    }
  }
}

vector<vector<int>> create_map(int n, int m, vector<int> a, vector<int> b) {
  if (n == 1) {
    return {{1}};
  }
  k.clear();
  g.assign(n + 1, {});
  t.assign(n + 1, {});
  adj.assign(n + 1, {});
  vis.assign(n + 1, 0);
  par.assign(n + 1, -1);
  dsu.p.assign(n + 1, -1);
  for (int i = 0; i < m; i++) {
    adj[a[i]].push_back(b[i]);
    adj[b[i]].push_back(a[i]);
  }
  auto [d1, d2] = longest_path(n);
  node = d2;
  for (int i = 0; i < m; i++) {
    if (g[a[i]].count(b[i])) {
      continue;
    }
    if (dsu.link(a[i], b[i])) {
      g[a[i]].insert(b[i]);
      g[b[i]].insert(a[i]);
    } else {
      t[a[i]].insert(b[i]);
      t[b[i]].insert(a[i]);
    }
  }
  dfs(d1);
  vector<int> res = {d1};
  for (int i = 1; i < n; i++) {
    int u = res.back(), v = k[i];
    if (par[v] != u) {
      u = par[u];
      res.push_back(u);
      while (u != par[v]) {
        u = par[u];
        res.push_back(u);
      }
    }
    res.push_back(v);
  }
  int N = 3 * n, idx = 0;
  vector<vector<int>> ans(N, vector<int>(N));
  for (int i = 0; i < N; i++) {
    if (idx >= res.size()) {
      fill(ans[i].begin(), ans[i].end(), res.back());
      continue;
    }
    int u = res[idx++];
    fill(ans[i].begin(), ans[i].end(), u);
    if (t[u].empty()) {
      continue;
    }
    fill(ans[i + 2].begin(), ans[i + 2].end(), u);
    int j = 0;
    vector<int> rem;
    for (auto v : t[u]) {
      if (j + 2 >= N) break;
      ans[i + 1][j++] = u;
      ans[i + 1][j++] = v;
      rem.push_back(v);
    }
    for (auto x : rem) {
      t[u].erase(x);
      t[x].erase(u);
    }
    for (; j < N; j++) {
      ans[i + 1][j] = u;
    }
    i += 2;
  }
  return ans;
}

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• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
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