Submission #893692

#	Time	Username	Problem	Language	Result	Execution time	Memory
893692		danikoynov	Event Hopping 2 (JOI21_event2)	C++14	32 / 100	3007 ms	3924 KiB

event2

/**
 ____ ____ ____ ____ ____ ____
||l |||e |||i |||n |||a |||d ||
||__|||__|||__|||__|||__|||__||
|/__\|/__\|/__\|/__\|/__\|/__\|

**/

#include<bits/stdc++.h>
#define endl '\n'

using namespace std;
typedef long long ll;

void speed()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
}

const int maxn = 1e5 + 10;

struct interval
{
    int l, r;
};

int n, k;
interval seg[maxn];
void input()
{
    cin >> n >> k;
    for (int i = 1; i <= n; i ++)
        cin >> seg[i].l >> seg[i].r;
}


bool cmp(interval it1, interval it2)
{
    if (it1.l != it2.l)
        return it1.l < it2.l;
    return it1.r > it2.r;
}

interval rel[maxn];
int m;
void get_relevant()
{
    vector < interval > vec;
    for (int i = 1; i <= n; i ++)
        vec.push_back(seg[i]);

    sort(vec.begin(), vec.end(), cmp);
    int cl = 1e9 + 10;
    for (int i = n - 1; i >= 0; i --)
    {
        if (vec[i].r >= cl)
        {
            continue;
        }
        rel[++ m] = vec[i];
        cl = vec[i].r;
    }

    reverse(rel + 1, rel + m + 1);
}

int len[2][maxn], pt[2][maxn], used[maxn];

void calc_pointers()
{
    int last = 0;
    for (int i = 1; i <= m; i ++)
    {
        if (used[i])
            continue;

        pt[0][i] = 0;
        if (last != 0)
            pt[0][i] = pt[0][last];
        while(rel[pt[0][i]].r <= rel[i].l)
            pt[0][i] ++;
        pt[0][i] --;
        while(pt[0][i] > 0 && used[pt[0][i]])
            pt[0][i] --;

        len[0][i] = len[0][pt[0][i]] + 1;
        last = i;
    }

    last = m + 1;
    for (int i = m; i > 0; i --)
    {
        if (used[i])
            continue;

        pt[1][i] = m + 1;
        if (last != m + 1)
            pt[1][i] = pt[1][last];
        while(rel[pt[1][i]].l >= rel[i].r)
            pt[1][i] --;
        pt[1][i] ++;
        while(pt[1][i] <= m && used[pt[1][m]])
            pt[1][m] ++;
        len[1][i] = len[1][pt[1][i]] + 1;
        last = i;
    }
}

bool intersect(interval a, interval b)
{
    if (a.l == b.l)
        return true;
    if (a.l > b.l)
        swap(a, b);
    if (a.r >= b.r)
        return true;
    return a.r > b.l;
}

void get_intersections(interval cur)
{
    for (int i = 1; i <= m; i ++)
        if (used[i] == 0 && intersect(rel[i], cur))
        used[i] = 2;

}

int get_longest()
{
    int ans = 0;
    for (int i = 1; i <= m; i ++)
    {
        if (used[i])
            continue;
        ans = max(ans, max(len[0][i], len[1][i]));
    }
    return ans;
}

void reverse_intersections()
{
    for (int i = 1; i <= m; i ++)
        if (used[i] == 2)
        used[i] = 0;
}

void apply_intersections()
{
    for (int i = 1; i <= m; i ++)
        if (used[i] == 2)
        used[i] = 1;
}

void create_sequence()
{
    vector < int > seq;
    for (int i = 1; i <= n && k > 0; i ++)
    {
        bool valid = true;
        for (int cur : seq)
        {
            if (intersect(seg[cur], seg[i]))
            {
                valid = false;
                break;
            }
        }

        if (!valid)
            continue;

        get_intersections(seg[i]);
        calc_pointers();
        int longest = get_longest();
        /**cout << i << " " << longest << endl;
        for (int j = 1; j <= m; j ++)
            cout << len[0][j] << " ";
        cout << endl;*/
        if (longest >= k - 1)
        {

            seq.push_back(i);
            k --;
            apply_intersections();
        }
        else
            reverse_intersections();
    }

    if (k != 0)
    {
        cout << -1 << endl;
        return;
    }
    for (int cur : seq)
        cout << cur << endl;
}
void solve()
{
    input();
    get_relevant();
    ///calc_pointers();
    create_sequence();
}

int main()
{
    solve();
    return 0;
}

/**
2 2
1 3
1 2
*/

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