Submission #1105230

#	Time	Username	Problem	Language	Result	Execution time	Memory
1105230		alexdd	Fire (BOI24_fire)	C++17	100 / 100	138 ms	7340 KiB

Main

#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9;
int n,m;
pair<int,int> v[200005];
int prefmax[200005];
int nxt[200005];
int get_ult(int lim)
{
    int st=0,dr=n,ans=0;
    while(st<=dr)
    {
        int mij=(st+dr)/2;
        if(v[mij].first <= lim)
        {
            ans = mij;
            st = mij+1;
        }
        else
            dr = mij-1;
    }
    return ans;
}
void calc_nxt()
{
    for(int i=1;i<=n;i++)
    {
        nxt[i] = prefmax[get_ult(v[i].second)];
        if(nxt[i]==i) nxt[i] = -1;
        //cout<<i<<" "<<nxt[i]<<" nxt\n";
    }
}
int main()
{
    cin>>n>>m;
    for(int i=1;i<=n;i++)
    {
        cin>>v[i].first>>v[i].second;
        if(v[i].first > v[i].second)
            v[i].second += m;
    }
    sort(v+1,v+1+n);
    prefmax[0] = -1;
    for(int i=1;i<=n;i++)
    {
        if(prefmax[i-1]==-1 || v[i].second > v[prefmax[i-1]].second)
            prefmax[i] = i;
        else
            prefmax[i] = prefmax[i-1];
    }
    calc_nxt();
    int rez=INF;
    for(int i=1;i<=n;i++)
    {
        if(v[i].second >= m)
        {
            int unde = prefmax[get_ult(v[i].second-m)];
            if(unde==i) unde = -1;

            int cur=unde,cnt=1;
            while(cur!=-1)
            {
                cnt++;
                if(v[cur].second >= v[i].first)
                    break;
                cur = nxt[cur];
            }
            if(cur!=-1) rez = min(rez, cnt);
        }
    }
    if(rez==INF)
        rez=-1;
    cout<<rez;
    return 0;
}

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