제출 #1111396

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1111396		gelastropod	Fire (BOI24_fire)	C++14	0 / 100	2075 ms	504 KiB

Main

#include<bits/stdc++.h>
using namespace std;
#define int long long

int M;
vector<pair<int, int>> tree;

void upd(int n, int x, int i)
{
    while (n <= M)
    {
        if (tree[n].first < x)
            tree[n] = {x, i};
        n += n & (-n);
    }
}

pair<int, int> qry(int a)
{
    pair<int, int> ans = {-1, -1};
    while (a > 0)
    {
        if (ans.first < tree[a].first)
            ans = tree[a];
        a -= a & (-a);
    }
    return ans;
}

signed main()
{
    int N, a, b;
    cin >> N >> M;
    tree = vector<pair<int, int>>(M + 1, {-1, -1});
    vector<pair<int, int>> pairs;
    vector<bool> works(N, true);
    for (int i = 0; i < N; i++)
    {
        cin >> a >> b;
        if (a > b) b += M;
        upd(a, b, i);
        pairs.push_back({a, b});
    }
    int anss = LLONG_MAX;
    for (int i = 0; i < N; i++)
    {
        if (!works[i]) continue;
        works[i] = false;
        int num = 1;
        int ca = pairs[i].first, cb = pairs[i].second;
        while (cb - ca < M)
        {
            auto z = qry(cb);
            if (z.first != -1 && works[z.second])
            {
                cb = max(cb, z.first);
                works[z.second] = false;
                num++;
            }
            else
                break;
        }
        if (cb - ca >= M)
            anss = min(num, anss);
    }
    if (anss == LLONG_MAX)
        cout << "-1\n";
    else
        cout << anss << '\n';
}

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