Submission #1240062

#TimeUsernameProblemLanguageResultExecution timeMemory
1240062madamadam3Sphinx's Riddle (IOI24_sphinx)C++20
13.50 / 100
25 ms1424 KiB
#include "sphinx.h"
#include <bits/stdc++.h>

using namespace std;

using vi =vector<int>;
using vvi =vector<vi>;

#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define FOR(i, a, b) for (int i = a; i < b; i++)
#define all(x) (x).begin(), (x).end()
#define bg(x) (x).begin()
#define en(x) (x).end()
#define sz(x) int((x).size())
#define rev(x) reverse(all(x))
#define srt(x) sort(all(x))
#define each(a, x) for (auto &a : x)
#define trace(x) for (auto &el : x) cout << el << " "

struct DSU {
  int n; vi par, siz;
  DSU() {};
  DSU(int N) {
    n = N; siz.assign(n, 1);
    par.resize(n); iota(all(par), 0);
  } 

  int find(int v) {
    if (par[v] == v) return v;
    return par[v] = find(par[v]);
  }

  void unite(int a, int b) {
    a = find(a); b = find(b);
    if (a != b) {
      if (siz[b] > siz[a]) swap(a, b);
      par[b] = a; siz[a] += siz[b]; 
    }
  }
};

int n, m;
vi x, y;
vvi adj;

vi find_colours(int N, vi X, vi Y) {
  n = N; m = sz(X); x = X; y = Y;
  adj.assign(n, vi());
  FOR(i, 0, m) adj[x[i]].pb(y[i]), adj[y[i]].pb(x[i]);

  vi graph(n, n);
  if (n == 2) {
    graph[0] = perform_experiment({-1, 0}) == 1 ? 0 : 1;
    graph[1] = perform_experiment({0, -1}) == 1 ? 0 : 1;
    return graph;
  }

  auto dsu = DSU(n);
  vector<int> reps; reps.push_back(0);

  FOR(i, 1, n) {
    int lo = 0, hi = sz(reps);
    // trace(reps); cout << "\n";
    
    while (lo < hi) {
      int mid = lo + (hi - lo) / 2;

      vi test(n, n);
      FOR(idx, 0, mid+1) test[reps[idx]] = -1;
      test[i] = -1;
      int expected = (mid == n - 2 ? 0 : 1) + (mid) + 1;

      // cout << "mid: " << mid << " perf: " << perform_experiment(test) << " expected: " << expected << "\n";
      if (perform_experiment(test) == expected) {
        hi = mid;
      } else {
        lo = mid+1;
      }
    }

    // cout << "lo: " << lo << "\n";
    if (lo >= sz(reps)) {
      reps.push_back(i);
    } else {
      dsu.unite(reps[lo], i);
    }
  }

  FOR(i, 0, n) {
    graph[i] = dsu.find(i);
  }
  return graph;
}
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