Submission #656537

#	Time	Username	Problem	Language	Result	Execution time	Memory
656537		Lobo	Event Hopping (BOI22_events)	C++17	20 / 100	129 ms	28808 KiB

events

#include<bits/stdc++.h>
using namespace std;
const long long inf = (long long) 1e18 + 10;
const int inf1 = (int) 1e9 + 10;
#define int long long
#define dbl long double
#define endl '\n'
#define sc second
#define fr first
#define mp make_pair
#define pb push_back
#define all(x) x.begin(), x.end()

const int maxn = 1e5+10;

int n, q, idord[maxn], lf[maxn], rg[maxn], nx[maxn][25];

void solve() {
    cin >> n >> q;
    vector<pair<pair<int,int>,int>> ord;
    for(int i = 1; i <= n; i++) {
        int l, r; cin >> l >> r;
        ord.pb(mp(mp(r,l),i));
    }
    sort(all(ord));
    for(int i = 1; i <= n; i++) {
        idord[ord[i-1].sc] = i;
        lf[i] = ord[i-1].fr.sc;
        rg[i] = ord[i-1].fr.fr;
    }

    for(int i = 1; i <= n; i++) {
        nx[i][0] = 0;
        int l = i+1;
        int r = n;
        while(l <= r) {
            int mid = (l+r)/2;
            if(lf[mid] <= rg[i]) {
                nx[i][0] = mid;
                l = mid+1;
            }
            else {
                r = mid-1;
            }
        }
    }

    for(int j = 1; j <= 20; j++) {
        for(int i = 1; i <= n; i++) {
            nx[i][j] = nx[nx[i][j-1]][j-1];
        }
    }

    while(q--) {
        int s,e; cin >> s >> e;
        s = idord[s];
        e = idord[e];

        int ans = 0;
        for(int j = 20; j >= 0; j--) {
            if(nx[s][j] != 0 && rg[nx[s][j]] <= rg[e]) {
                ans+= (1<<j);
                s = nx[s][j];
            }
        }

        if(s == e) {
            cout << ans << endl;
        }
        else if(lf[e] <= rg[s] && rg[s] <= rg[e]) {
            cout << ans+1 << endl;
        }
        else {
            cout << "impossible" << endl;
        }
    }
}

int32_t main() {
    ios::sync_with_stdio(false); cin.tie(0);

    // freopen("in.in", "r", stdin);
    // freopen("out.out", "w", stdout);
    int tt = 1;
    // cin >> tt;
    while(tt--) {
        solve();
    }

}

• Subtask 1: 0 / 10
• Subtask 2: 0 / 10
• Subtask 3: 0 / 15
• Subtask 4: 0 / 15
• Subtask 5: 20 / 20
• Subtask 6: 0 / 30