Submission #1095803

#	Time	Username	Problem	Language	Result	Execution time	Memory
1095803		SalihSahin	Fire (BOI24_fire)	C++14	100 / 100	1463 ms	181180 KiB

Main

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

const int N = 2e5 + 5;
const int K = 20;
const int mod = 1e9 + 7;

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
    int n, m;
    cin>>n>>m;
    vector<pair<int, int> > a(n);
    set<int> st;
    for(int i = 0; i < n; i++){
        cin>>a[i].first>>a[i].second;
        st.insert(a[i].first);
        st.insert(a[i].second);
        st.insert(a[i].first + m);
        st.insert(a[i].second + m);
    }
    map<int, int> pos;
    int here = 0;
    vector<int> vals;
    vals.pb(0);
    for(auto itr: st){
        pos[itr] = ++here;
        vals.pb(itr);
    }

    vector<int> upd(here + 1);
    for(int i = 0; i < n; i++){
        int f = a[i].first, s = a[i].second;
        if(f > s){
            upd[pos[f]] = max(upd[pos[f]], s + m);
        }
        else{
            upd[pos[f]] = max(upd[pos[f]], s);
            upd[pos[f + m]] = max(upd[pos[f]], s + m);
        }
    }
    vector<vector<int> > lift(here + 1, vector<int>(K));
    int val = 0;

    for(auto itr: st){
        val = max(val, upd[pos[itr]]);
        lift[pos[itr]][0] = pos[val];
    }
    
    for(int i = 1; i < K; i++){
        for(int j = 1; j <= here; j++){
            lift[j][i] = lift[lift[j][i-1]][i-1];
        }
    }

    int ans = n + 23;
    for(int st = 0; st < n; st++){
        int f = a[st].first;
        int cnt = 0;
        bool ok = 1;
        int r = pos[f];
        
        for(int bt = K-1; bt >= 0; bt--){
            if(vals[lift[r][bt]] < m + f){
                cnt += (1 << bt);
                r = lift[r][bt];
            }
        }

        if(vals[lift[r][0]] >= m + f) ans = min(ans, cnt + 1);
    }

    if(ans == n + 23) cout<<-1<<endl;
    else cout<<ans<<endl;
    return 0;
}

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:61:14: warning: unused variable 'ok' [-Wunused-variable]
   61 |         bool ok = 1;
      |              ^~

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