Submission #659178

#	Time	Username	Problem	Language	Result	Execution time	Memory
659178		evenvalue	Carnival Tickets (IOI20_tickets)	C++17	100 / 100	2016 ms	202244 KiB

tickets

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

template<typename T>
using min_heap = priority_queue<T, vector<T>, greater<T>>;
template<typename T>
using max_heap = priority_queue<T, vector<T>, less<T>>;

using int64 = long long;
using ld = long double;

constexpr int kInf = 1e9 + 10;
constexpr int64 kInf64 = 1e15 + 10;
constexpr int kMod = 1e9 + 7;

struct ticket {
  int value;
  int color;
  int group;

  bool operator<(const ticket &other) const {
    return (value == other.value ? group < other.group : value < other.value);
  }

  bool operator>(const ticket &other) const {
    return (value == other.value ? group > other.group : value > other.value);
  }
};

struct ticket_pair {
  ticket one;
  ticket two;
  int priority;

  int value() const {
    return one.value + two.value;
  }

  bool operator<(const ticket_pair &other) const {
    return (value() == other.value() ? priority < other.priority : value() < other.value());
  }

  bool operator>(const ticket_pair &other) const {
    return (value() == other.value() ? priority < other.priority : value() > other.value());
  }
};

int64 find_maximum(const int k, const vector<vector<int>> X) {
  const int n = (int) X.size();   //number of colours
  const int m = (int) X[0].size();//number of tickets
  const int choose = n * k;       //number of tickets to choose

  vector<vector<ticket>> tickets(n, vector<ticket>(m));
  for (int color = 0; color < n; color++) {
    for (int group = 0; group < m; group++) {
      tickets[color][group].value = X[color][group];
      tickets[color][group].color = color;
      tickets[color][group].group = group;
    }
  }

  vector<max_heap<ticket>> max_ticket(n);
  for (int color = 0; color < n; color++) {
    for (ticket &t : tickets[color]) {
      max_ticket[color].push(t);
    }
  }

  max_heap<ticket_pair> pq;
  for (auto color : tickets) {
    sort(color.begin(), color.end());
    for (int i = 0; i < k; i++) {
      const int j = m - k + i;
      pq.push({color[i], color[j], i});
    }
  }

  assert(pq.size() == choose);

  vector<vector<ticket>> positive(n);
  while (pq.size() > choose / 2) {
    const ticket t1 = pq.top().one;
    const ticket t2 = pq.top().two;
    positive[t2.color].push_back(t2);
    pq.pop();
  }

  vector<vector<ticket>> negative(n);
  while (not pq.empty()) {
    const ticket t = pq.top().one;
    negative[t.color].push_back(t);
    pq.pop();
  }

  auto size_sum = [&](const vector<vector<ticket>> &foo) {
    int sum = 0;
    for (const auto &color : foo) {
      sum += color.size();
    }
    return sum;
  };

  assert(size_sum(positive) == choose / 2);
  assert(size_sum(negative) == choose / 2);

  int64 score = 0;
  vector<vector<int>> s(n, vector<int>(m, -1));

  for (int round = 0; round < k; round++) {
    vector<int> color(n);
    iota(color.begin(), color.end(), 0);

    auto delta = [&](const int i) {
      return (int)positive[i].size() - (int)negative[i].size();
    };

    sort(color.begin(), color.end(), [&](const int i, const int j) {
      return delta(i) > delta(j);
    });

    for (int i = 0; i < n; i++) {
      auto &v = (i < n / 2 ? positive : negative);
      const ticket t = v[color[i]].back();
      s[t.color][t.group] = round;
      score += (i < n / 2 ? t.value : -t.value);
      v[color[i]].pop_back();
    }
  }

  allocate_tickets(s);
  return score;
}

Compilation message (stderr)

In file included from /usr/include/c++/10/cassert:44,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:33,
                 from tickets.cpp:2:
tickets.cpp: In function 'int64 find_maximum(int, std::vector<std::vector<int> >)':
tickets.cpp:79:20: warning: comparison of integer expressions of different signedness: 'std::priority_queue<ticket_pair, std::vector<ticket_pair, std::allocator<ticket_pair> >, std::less<ticket_pair> >::size_type' {aka 'long unsigned int'} and 'const int' [-Wsign-compare]
   79 |   assert(pq.size() == choose);
      |          ~~~~~~~~~~^~~~~~~~~
tickets.cpp:82:20: warning: comparison of integer expressions of different signedness: 'std::priority_queue<ticket_pair, std::vector<ticket_pair, std::allocator<ticket_pair> >, std::less<ticket_pair> >::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   82 |   while (pq.size() > choose / 2) {
      |          ~~~~~~~~~~^~~~~~~~~~~~
tickets.cpp:83:18: warning: variable 't1' set but not used [-Wunused-but-set-variable]
   83 |     const ticket t1 = pq.top().one;
      |                  ^~

• 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