Submission #930414

#	Time	Username	Problem	Language	Result	Execution time	Memory
930414		boris_mihov	Event Hopping 2 (JOI21_event2)	C++17	1 / 100	3043 ms	5928 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;
std::vector <int> remaining;

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

int canAdd(int idx)
{
    int cntLeft = sol.size();
    for (const int &i : ans)
    {
        if (intersecting(idx, i))
        {
            return -1;
        }
    }

    int maxPopped = 0;
    for (const int &i : sol)
    {
        if (intersecting(idx, i))
        {
            maxPopped = std::max(maxPopped, r[i]);
            cntLeft--;
        }
    }

    int allowedTo = INF;
    for (const int &i : sol)
    {
        if (l[i] >= maxPopped)
        {
            allowedTo = std::min(allowedTo, l[i]);
        }
    }

    int coolIdx = 0;
    for (const int &i : remaining)
    {
        if (r[i] <= allowedTo && l[i] >= r[idx])
        {
            // std::cout << coolUIDx
            assert(coolIdx == 0);
            coolIdx = i;
        }
    }
    
    if  ((coolIdx != 0) + cntLeft + ans.size() + 1 >= k)
    {
        return coolIdx;
    } else
    {
        return -1;
    }
}

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

    sol = sol2;

    std::vector <int> rem2;
    for (const int &i : remaining)
    {
        if (!intersecting(idx, i))
        {
            rem2.push_back(i);
        }
    }

    remaining = rem2;
}

void solve()
{
    std::vector <std::pair <int, std::pair <int,bool>>> v;
    for (int i = 1 ; i <= n ; ++i)
    {
        v.push_back({l[i], {i, false}});
        v.push_back({r[i], {i, true}});
    }
    
    int cnt = 0;
    int last = 0;
    std::sort(v.begin(), v.end());
    for (int i = 0 ; i < 2 * n ; ++i)
    {
        cnt += (v[i].first > last);
        last = v[i].first;

        if (v[i].second.second) r[v[i].second.first] = cnt;
        else l[v[i].second.first] = cnt;
    }

    // std::cout << n << ' ' << k << '\n';
    // for (int i = 1 ; i <= n ; ++i)
    // {
    //     std::cout << l[i] << ' ' << r[i] << '\n';
    // }

    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]);
        } else
        {
            remaining.push_back(perm[i]);
        }
    }

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

    // std::cout << "sol is\n";
    // for (const int &idx : sol)
    // {
    //     std::cout << idx << ' ' << l[idx] << ' ' << r[idx] << '\n';
    // }

    for (int i = 1 ; i <= n && ans.size() < k ; ++i)
    {
        int res = canAdd(i);
        // std::cout << "res: " << res << 
        if (res != -1)
        {
            ans.push_back(i);
            removeIntersecting(i);
            if (res != 0)
            {
                // std::cout << "          bonus: " << i << ' ' << res << '\n';
                sol.push_back(res);
                for (int &i : remaining)
                {
                    if (i == res)
                    {
                        std::swap(i, remaining.back());
                        remaining.pop_back();
                        break;
                    }
                }
            }
        }
    }

    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 'int canAdd(int)':
event2.cpp:70:52: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   70 |     if  ((coolIdx != 0) + cntLeft + ans.size() + 1 >= k)
      |          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~
event2.cpp: In function 'void solve()':
event2.cpp:148:20: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
  148 |     if (sol.size() < k)
      |         ~~~~~~~~~~~^~~
event2.cpp:160:43: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
  160 |     for (int i = 1 ; i <= n && ans.size() < k ; ++i)
      |                                ~~~~~~~~~~~^~~

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