Submission #970856

#	Time	Username	Problem	Language	Result	Execution time	Memory
970856		kl0989e	Event Hopping (BOI22_events)	C++17	100 / 100	152 ms	29880 KiB

events

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

#define ll long long
#define fi first
#define se second
#define pb push_back
#define vi vector<int>
#define pi pair<int, int>
#define all(x) (x).begin(),(x).end()

const int maxn=1e5+10;
const int LOG=int(log2(maxn))+1;
vector<pi> events(maxn);
vector<vi> table(maxn,vi(LOG,-1));
vector<vector<pi>> rmq(LOG,vector<pi>(maxn,{1000000010,-1}));
vi pow2(LOG,1);

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    int n,q;
    cin >> n >> q;
    vi b;
    for (int i = 0; i < n; i++) {
        cin >> events[i].fi >> events[i].se;
        b.push_back(events[i].se);
    }
    sort(all(b));
    b.erase(unique(all(b)),b.end());
    for (int i=0; i<n; i++) {
        int r=lower_bound(all(b),events[i].se)-b.begin();
        rmq[0][r]=min(rmq[0][r],{events[i].fi,i});
    }
    for (int i=0; i+1<LOG; i++) {
        for (int j=0; j+(1<<(i+1))<=n; j++) {
            rmq[i+1][j]=min(rmq[i][j],rmq[i][j+(1<<i)]);
        }
    }
    for (int i=0; i<n; i++) {
        int l=lower_bound(all(b),events[i].fi)-b.begin();
        int r=lower_bound(all(b),events[i].se)-b.begin();
        int h=31-__builtin_clz(r-l+1);
        table[i][0]=min(rmq[h][l],rmq[h][r+1-(1<<h)]).se;
    }
    for (int i=0; i+1<LOG; i++) {
        for (int j = 0; j < n; j++) {
            table[j][i+1]=table[table[j][i]][i];
        }
    }
    int x,y,l;
    for (int i=0; i<q; i++) {
        l=1;
        cin >> x >> y;
        x--;
        y--;
        if (x==y) {
            cout << "0\n";
            continue;
        }
        if (events[y].fi<=events[x].se && events[x].se<=events[y].se) {
            cout << "1\n";
            continue;
        }
        for (int i=LOG-1; i>=0; i--) {
            if (events[x].se<events[table[y][i]].fi) {
                l+=1<<i;
                y=table[y][i];
            }
        }
        y=table[y][0];
        if (events[x].se<events[y].fi || events[x].se>events[y].se) {
            cout << "impossible\n";
        }
        else {
            cout << l+(events[x].se>=events[y].fi) << "\n";
        }
    }
    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