Submission #930279

#	Time	Username	Problem	Language	Result	Execution time	Memory
930279		boris_mihov	Event Hopping 2 (JOI21_event2)	C++17	1 / 100	3010 ms	3264 KiB

event2

#include <algorithm>
#include <iostream>
#include <numeric>
#include <cassert>
#include <cstring>
#include <vector>
#include <queue>
#include <stack>
#include <set>

typedef long long llong;
const int MAXN = 100000 + 10;
const int INF  = 2e9;

int n, k;
int l[MAXN];
int r[MAXN];
int perm[MAXN];

std::vector <int> sol;
std::vector <int> ans;

bool intersecting(int x, int y)
{
  return std::max(l[x], l[y]) < std::min(r[x], r[y]);
}

bool canAdd(int idx)
{
  int cntLeft = sol.size();
  for (const int &i : ans)
  {
    if (intersecting(idx, i))
    {
      return false;
    }
  }

  for (const int &i : sol)
  {
    if (intersecting(idx, i))
    {
      cntLeft--;
    }
  }

  return cntLeft + ans.size() + 1 >= k;
}

void removeIntersecting(int idx)
{
  std::vector <int> sol2;
  int cntLeft = sol.size();
  for (const int &i : sol)
  {
    if (!intersecting(idx, i))
    {
      sol2.push_back(i);
    }
  }

  sol = sol2;
}

void solve()
{
  std::iota(perm + 1, perm + 1 + n, 1);
  std::sort(perm + 1, perm + 1 + n, [&](int x, int y)
            {
              return r[x] < r[y] || (r[x] == r[y] && l[x] > l[y]);  
            });

  for (int i = 1 ; i <= n ; ++i)
  {
    if (sol.empty() || !intersecting(sol.back(), perm[i]))
    {
      sol.push_back(perm[i]);
    }
  }

  if (sol.size() < k)
  {
    std::cout << -1 << '\n';
    return;
  }

  for (int i = 1 ; i <= n && ans.size() < k ; ++i)
  {
    if (canAdd(i))
    {
      ans.push_back(i);
      removeIntersecting(i);
    }
  }

  assert(ans.size() == k);
  for (const int &idx : ans)
  {
    std::cout << idx << '\n';
  }
}

void input()
{
  std::cin >> n >> k;
  for (int i = 1 ; i <= n ; ++i)
  {
    std::cin >> l[i] >> r[i];
    // l[i]++;
  }
}

void fastIOI()
{
  std::ios_base :: sync_with_stdio(0);
  std::cout.tie(nullptr);
  std::cin.tie(nullptr);
}   

int main()
{
  fastIOI();
  input();
  solve();

  return 0;
}

Compilation message (stderr)

event2.cpp: In function 'bool canAdd(int)':
event2.cpp:47:35: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   47 |   return cntLeft + ans.size() + 1 >= k;
      |          ~~~~~~~~~~~~~~~~~~~~~~~~~^~~~
event2.cpp: In function 'void removeIntersecting(int)':
event2.cpp:53:7: warning: unused variable 'cntLeft' [-Wunused-variable]
   53 |   int cntLeft = sol.size();
      |       ^~~~~~~
event2.cpp: In function 'void solve()':
event2.cpp:81:18: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   81 |   if (sol.size() < k)
      |       ~~~~~~~~~~~^~~
event2.cpp:87:41: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   87 |   for (int i = 1 ; i <= n && ans.size() < k ; ++i)
      |                              ~~~~~~~~~~~^~~
In file included from /usr/include/c++/10/cassert:44,
                 from event2.cpp:4:
event2.cpp:96:21: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   96 |   assert(ans.size() == k);
      |          ~~~~~~~~~~~^~~~

• Subtask 1: 0 / 7
• Subtask 2: 1 / 1
• Subtask 3: 0 / 31
• Subtask 4: 0 / 61