Submission #1111528

#	Time	Username	Problem	Language	Result	Execution time	Memory
1111528		gelastropod	Fire (BOI24_fire)	C++14	0 / 100	2076 ms	592 KiB

Main

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

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});
    set<pair<int, int>> pairss;
    vector<pair<int, int>> pairs;
    for (int i = 0; i < N; i++)
    {
        cin >> a >> b;
        if (a > b) b += M;
        pairss.insert({a, b});
    }
    int counter = 0;
    while (!pairss.empty())
    {
        pairs.push_back(*pairss.begin());
        upd(pairss.begin()->first, pairss.begin()->second, counter);
        counter++;
        pairss.erase(pairss.begin());
    }
    int anss = INT_MAX;
    for (int i = 0; i < pairs.size(); i++)
    {
        int num = 1;
        int ca = pairs[i].first, cb = pairs[i].second;
        int prev = i;
        while (cb - ca < M)
        {
            auto z = qry(min(cb, M));
            if (z.first != -1 && z.second != prev && z.second != -1)
            {
                cb = z.first;
                num++;
            }
            else
                break;
            prev = z.second;
        }
        if (cb - ca >= M)
            anss = min(num, anss);
    }
    if (anss == INT_MAX)
        cout << "-1\n";
    else
        cout << anss << '\n';
}

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:51:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   51 |     for (int i = 0; i < pairs.size(); i++)
      |                     ~~^~~~~~~~~~~~~~

• Subtask 1: 0 / 14
• Subtask 2: 0 / 17
• Subtask 3: 0 / 9
• Subtask 4: 0 / 13
• Subtask 5: 0 / 21
• Subtask 6: 0 / 26