Submission #1279570

#	Time	Username	Problem	Language	Result	Execution time	Memory
1279570		avighna	Sphinx's Riddle (IOI24_sphinx)	C++20	43 / 100	337 ms	1600 KiB

sphinx

#include <bits/stdc++.h>

int perform_experiment(std::vector<int> E);

int n;
std::vector<std::vector<int>> adj;

int query(const std::vector<int> &c) {
  if (std::find(c.begin(),c.end(), -1)!=c.end()) {
    return perform_experiment(c);
  }
  int ans = 0;
  std::queue<int> q;
  std::vector<bool> vis(n);
  for (int i = 0; i < n; ++i) {
    if (vis[i]) {
      continue;
    }
    vis[i]=true;
    ans++;
    q.push(i);
    while (!q.empty()) {
      int u = q.front();
      q.pop();
      for (int &i : adj[u]) {
        if (!vis[i] and c[u] == c[i]) {
          vis[i]=true;
          q.push(i);
        }
      }
    }
  }
  return ans;
}

class dsu {
private:
  int n;
  std::vector<int> par, size;
  std::vector<std::vector<int>> comp_m;

public:
  dsu(int n) : n(n), par(n), size(n, 1), comp_m(n) {
    std::iota(par.begin(), par.end(), 0);
    for (int i=0;i<n;++i){comp_m[i].push_back(i);}
  }

  int root(int u) { return u == par[u] ? u : par[u] = root(par[u]); }

  void merge(int u,int v) {
    u=root(u),v=root(v);
    if (u==v){return;}
    if (size[u]<size[v]){std::swap(u,v);}
    for (int &i:comp_m[v]){
      comp_m[u].push_back(i);
    }
    par[v]=u;
    size[u]+=size[v];
  }

  const std::vector<int> &comp(int u) {return comp_m[root(u)];}
};

std::vector<int> find_colours(int N, std::vector<int> x, std::vector<int> y) {
  n = N;
  adj.resize(n);
  for (int i = 0; i < x.size(); ++i) {
    adj[x[i]].push_back(y[i]);
    adj[y[i]].push_back(x[i]);
  }

  dsu dsu(n);
  for (int u=1;u<n;++u){
    std::vector<bool> seen(n);
    std::vector<int> nodes;
    for (int i :adj[u]) {
      i=dsu.root(i);
      if (i>u or seen[i]){continue;}
      seen[i]=true;nodes.push_back(i);
    }
    auto has=[&](int from, int till){
      std::vector<int> q(n,n);
      for (int i=from;i<=till;++i){
        for (int u:dsu.comp(nodes[i])){
          q[u]=dsu.root(nodes[i]);
        }
      }
      q[u]=n+1;
      int bef=query(q);
      for (int i=from;i<=till;++i){
        for (int u:dsu.comp(nodes[i])){
          q[u]=-1;
        }
      }
      q[u]=-1;
      int aft=query(q);
      return bef-aft;
    };
    int times=has(0,nodes.size()-1);
    for (int _=0,fr=-1;_<times;++_){
      fr=*std::ranges::partition_point(std::views::iota(fr+1,int(nodes.size())),[&](int i) {
        return has(fr+1,i)==0;
      });
      dsu.merge(u,nodes[fr]);
    }
  }

  std::vector<std::vector<int>> nadj(n);
  for (int u=0;u<n;++u) {
    for (int &i:adj[u]) {
      if (dsu.root(u)!=dsu.root(i)) {
        nadj[dsu.root(u)].push_back(dsu.root(i));
      }
    }
  }
  for (int u=0;u<n;++u) {
    std::sort(nadj[u].begin(),nadj[u].end());
    nadj[u].erase(std::unique(nadj[u].begin(),nadj[u].end()), nadj[u].end());
  }

  std::vector<int> dist(n);
  std::queue<int> q;
  std::vector<bool> vis(n);
  for (int i = 0; i < n; ++i) {
    if (vis[i] or dsu.root(i)!=i) {continue;}
    vis[i]=true;
    q.push(i);
    while (!q.empty()) {
      int u = q.front();q.pop();
      for (int &i : nadj[u]) {
        if (!vis[i]) {
          vis[i]=true;
          dist[i]=dist[u]+1;
          q.push(i);
        }
      }
    }
  }

  std::vector<int> a,b;
  for (int u=0;u<n;++u) {
    if (dsu.root(u)!=u) {continue;}
    (dist[u]%2?a:b).push_back(u);
  }
  
  std::vector<int> ans(n);
  if (a.empty()) {
    for (int c=0;c<n;++c){
      std::vector<int> q(n,-1);
      q[0]=c;
      if (query(q)==1){
        ans[b[0]]=c;break;
      }
    }
  }else {
  for (auto &[a,b] : std::array<std::pair<std::vector<int>,std::vector<int>>,2>({{a,b},{b,a}})) {
    for (int c=0;c<n;++c) {
      auto has=[&](int from, int till) {
        std::vector<int> q(n,n);
        for (int &i : b) {
          for (auto &u : dsu.comp(i)) {
            q[u]=n+1;
          }
        }
        for (int i=from;i<=till;++i){
          for (auto &u : dsu.comp(a[i])) {
            q[u]=a[i];
          }
        }
        int bef=query(q);
        for (int &i : b) {
          for (auto &u : dsu.comp(i)) {
            q[u]=c;
          }
        }
        for (int i=from;i<=till;++i){
          for (auto &u : dsu.comp(a[i])) {
            q[u]=-1;
          }
        }
        int aft=query(q);
        return bef-aft;
      };
      int fr=-1;
      while (true) {
        if (has(fr+1,a.size()-1)==0) {break;}
        fr = *std::ranges::partition_point(std::views::iota(fr+1,int(a.size())), [&](int i) {
          return has(fr+1,i)==0;
        });
        ans[a[fr]]=c;
      }
    }
  }
  }

  for (int i=0;i<n;++i){
    ans[i]=ans[dsu.root(i)];
  }
  return ans;
}

• Subtask 0: 0 / 0
• Subtask 1: 3 / 3
• Subtask 2: 7 / 7
• Subtask 3: 33 / 33
• Subtask 4: 0 / 21
• Subtask 5: 0 / 36