Submission #425242

#	Time	Username	Problem	Language	Result	Execution time	Memory
425242		peijar	Carnival Tickets (IOI20_tickets)	C++17	100 / 100	1290 ms	113768 KiB

tickets

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

long long find_maximum(int k, vector<vector<int>> x) {
  int n = x.size();
  int m = x[0].size();
  vector<vector<int>> answer(n, vector<int>(m, -1));

  vector<vector<int>> side(n, vector<int>(m, -1));

  priority_queue<tuple<int, int, int>> pq;
  long long sol = 0;

  for (int i = 0; i < n; ++i) {
    for (int j(0); j < k; ++j) {
      int other = m - k + j;
      sol -= x[i][j];
      side[i][j] = 0;
      pq.emplace(x[i][j] + x[i][other], i, j);
    }
  }
  while ((int)pq.size() > n * k / 2) {
    auto [delta, i, j] = pq.top();
    int other = m - k + j;
    pq.pop();
    sol += delta;
    side[i][j] = -1;
    side[i][other] = 1;
  }

  vector<vector<int>> posLeft(n), posRight(n);
  for (int i = 0; i < n; ++i)
    for (int j = 0; j < m; ++j) {
      if (side[i][j] == 1)
        posRight[i].push_back(j);
      else if (side[i][j] == 0)
        posLeft[i].push_back(j);
    }
  for (int round = 0; round < k; ++round) {
    vector<bool> picked(n);
    int gaucheNec = n / 2, droiteNec = n / 2;
    for (int col = 0; col < n; ++col) {
      if (posLeft[col].empty()) {
        picked[col] = true;
        answer[col][posRight[col].back()] = round;
        posRight[col].pop_back();
        droiteNec--;
      } else if (posRight[col].empty()) {
        picked[col] = true;
        answer[col][posLeft[col].back()] = round;
        posLeft[col].pop_back();
        gaucheNec--;
      }
    }
    for (int col = 0; col < n; ++col) {
      if (picked[col])
        continue;
      assert(!posLeft[col].empty() and !posRight[col].empty());
      if (gaucheNec > 0) {
        answer[col][posLeft[col].back()] = round;
        posLeft[col].pop_back();
        gaucheNec--;
      } else {
        assert(droiteNec > 0);
        answer[col][posRight[col].back()] = round;
        posRight[col].pop_back();
        droiteNec--;
      }
    }
  }
  allocate_tickets(answer);
  return sol;
}

• Subtask 1: 11 / 11
• Subtask 2: 16 / 16
• Subtask 3: 14 / 14
• Subtask 4: 14 / 14
• Subtask 5: 12 / 12
• Subtask 6: 23 / 23
• Subtask 7: 10 / 10