Submission #584395

#	Time	Username	Problem	Language	Result	Execution time	Memory
584395		alireza_kaviani	Event Hopping (BOI22_events)	C++17	100 / 100	141 ms	13616 KiB

events

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

typedef long long ll;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;

#define all(x)      (x).begin(),(x).end()
#define X           first
#define Y           second
#define sep         ' '
#define endl        '\n'
#define SZ(x)       ll(x.size())

const ll MAXN = 1e6 + 10;
const ll LOG = 22;
const ll INF = 8e18;
const ll MOD = 1e9 + 7; //998244353; //1e9 + 9;

int n , q , S[MAXN] , E[MAXN] , nxt[LOG][MAXN];
vector<pair<pii , int>> stk;
vector<int> vec;

int cmp(int x , int y){
    if(E[x] != E[y])    return E[x] < E[y];
    return S[x] < S[y];
}

int main() {
    ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

    cin >> n >> q;
    for(int i = 1 ; i <= n ; i++){
        cin >> S[i] >> E[i];
        vec.push_back(i);
    }
    sort(all(vec) , cmp);
    for(auto& i : vec){
        while(SZ(stk) && S[i] <= stk.back().X.Y){
            stk.pop_back();
        }
        stk.push_back({{E[i] , S[i]} , i});
        nxt[0][i] = lower_bound(all(stk) , pair<pii , int>({{S[i] , -MOD} , -MOD})) -> Y;
        //cout << i << sep << nxt[0][i] << endl;
    }
    for(int i = 1 ; i < LOG ; i++){
        for(int j = 1 ; j <= n ; j++){
            nxt[i][j] = nxt[i - 1][nxt[i - 1][j]];
        }
    }
    while(q--){
        int v , u;
        cin >> v >> u;
        if(E[u] < E[v]){
            cout << "impossible" << endl;
            continue;
        }
        if(v == u){
            cout << 0 << endl;
            continue;
        }
        if(S[u] <= E[v]){
            cout << 1 << endl;
            continue;
        }
        int ans = 0;
        for(int i = LOG - 1 ; i >= 0 ; i--){
            if(S[nxt[i][u]] > E[v]){
                u = nxt[i][u];
                ans += (1 << i);
            }
        }
        if(E[v] < S[nxt[0][u]]){
            cout << "impossible" << endl;
            continue;
        }
        cout << ans + 2 << endl;
    }

    return 0;
}
/*

*/

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 15 / 15
• Subtask 4: 15 / 15
• Subtask 5: 20 / 20
• Subtask 6: 30 / 30