Submission #930277

#	Time	Username	Problem	Language	Result	Execution time	Memory
930277		boris_mihov	Event Hopping 2 (JOI21_event2)	C++17	1 / 100	3085 ms	3480 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];  
    });

    int end = 0;
    for (int i = 1 ; i <= n ; ++i)
    {
        if (l[perm[i]] >= end)
        {
            sol.push_back(perm[i]);
            end = r[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:47:37: 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:53:9: warning: unused variable 'cntLeft' [-Wunused-variable]
   53 |     int cntLeft = sol.size();
      |         ^~~~~~~
event2.cpp: In function 'void solve()':
event2.cpp:83:20: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   83 |     if (sol.size() < k)
      |         ~~~~~~~~~~~^~~
event2.cpp:89:43: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   89 |     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:98:23: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   98 |     assert(ans.size() == k);
      |            ~~~~~~~~~~~^~~~

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