Submission #292713

#	Time	Username	Problem	Language	Result	Execution time	Memory
292713		Haunted_Cpp	Simurgh (IOI17_simurgh)	C++17	51 / 100	247 ms	3968 KiB

simurgh

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

const int MAX_N = 500 + 5;

vector<vector<pair<int, int>>> g(MAX_N);
bitset<MAX_N> vis;
bitset<MAX_N * MAX_N> invalid;
bitset<MAX_N * MAX_N> is_op;
vector<int> span, par, s, best_way, u, v;

int n;

void reset() {
  for (int i = 0; i < n; i++) {
    par[i] = i;
    s[i] = 1;
  }
}

int root(int x) {
  if (x == par[x]) return x;
  return par[x] = root(par[x]);
}

void join(int a, int b) {
  a = root(a);
  b = root(b);
  if (a == b) return;
  if (s[a] < s[b]) swap(a, b);
  par[b] = a;
  s[a] += s[b];
}

bool is(int a, int b) {
  return root(a) == root(b);
}

bool works() {
  for (auto to : span) {
    const int st = u[to];
    const int et = v[to];
    if (is(st, et)) return false;
    join(st, et);
  }
  return true;
}

void get_any(int node) {
  vis[node] = 1;
  for (auto [nxt, to] : g[node]) {
    if (!vis[nxt]) {
      vis[nxt] = 1;
      span.emplace_back(to);
      get_any(nxt);
    }
  }  
}

vector<int> find_roads(int n, vector<int> u, vector<int> v) {
  ::n = n;
  ::u = u;
  ::v = v;
  const int m = v.size();
  const int t = n - 1;
  par = s = vector<int>(n);
  for (int i = 0; i < m; i++) {
    const int st = u[i];
    const int et = v[i];
    g[st].emplace_back(et, i);
    g[et].emplace_back(st, i);
  }
  get_any(0);
  int score = count_common_roads(span);
  if (score == t) {
    return span;
  }
  for (auto &edge : span) {
    int starting_edge = edge;
    bool swap = false;
    reset();
    best_way.clear();
    for (auto add_back : span) {
      if (add_back == edge) continue;
      join(u[add_back], v[add_back]);
    }
    for (int i = 0; i < m; i++) {
      const int st = u[i];
      const int et = v[i];
      if (is(st, et) == false && !invalid[i]) {
        best_way.emplace_back(i);
      }
    }
    //~ for (auto to : 
    vector<pair<int, int>> sc;
    for (auto i : best_way) {
      edge = i;
      assert(!invalid[i]);
      int nxt_score = count_common_roads(span);
      sc.emplace_back(edge, nxt_score);
      if (nxt_score > score) {
        score = nxt_score;
        swap = true;
        break;
      }
      if (nxt_score < score) {
        invalid[i] = 1;
      }
    }
    if (score == t) {
      return span;
    }
    if (!swap) {
      edge = starting_edge;
      for (auto [nxt, res] : sc) {
        if (res < score) {
          invalid[nxt] = 1;
        }
      }
    } else {
      for (auto [nxt, res] : sc) {
        if (res <= score) {
          invalid[nxt] = 1;
        }
      }
    }
  }
  return span;
}

• Subtask 1: 13 / 13
• Subtask 2: 17 / 17
• Subtask 3: 21 / 21
• Subtask 4: 0 / 19
• Subtask 5: 0 / 30