Submission #721863

#	Time	Username	Problem	Language	Result	Execution time	Memory
721863		MDSPro	Event Hopping (BOI22_events)	C++17	0 / 100	81 ms	13756 KiB

events

#include "bits/stdc++.h"
 
using namespace std;
 
int main(){
    cin.tie(0)->sync_with_stdio(0);
 
    int n,q; cin >> n >> q;
    vector<tuple<int,int,int>> ev;
    for(int i = 0; i < n; ++i){
        int x,y; cin >> x >> y;
        ev.emplace_back(x,y,i+1);
    }
 
    sort(ev.begin(),ev.end());  
 
    vector<int> nw_order(n+1);
    vector<int> left(n),right(n);
    for(int i = 0; i < n; ++i) {
        left[i] = get<0>(ev[i]);
        right[i] = get<1>(ev[i]);
        nw_order[get<2>(ev[i])] = i;
    }
 
    vector<vector<int>> nxt(23,vector<int>(n+1));
    nxt[0][n] = n;
 
    int r = 0;
    for(int i = 0; i < n; ++i){
        while(r+1 < n && left[r+1] <= right[i]) r++;
 
        if(i != r) nxt[0][i] = r;
        else nxt[0][i] = n;
    }
    for(int i = 1; i < 23; ++i) {
        for(int j = 0; j <= n; ++j){
            nxt[i][j] = nxt[i-1][nxt[i-1][j]];
        }
    }
 
    auto get = [&](int x, int y){
        if(x == y) return 0;
        if(nxt[0][x] == n) return -1;
        if(nxt[1][x] > y) return 1;
        int cur = 0;
        for(int i = 22; i >= 0; --i){
            if(nxt[i][x] < y) {
                cur += (1<<i);
                x = nxt[i][x];
            }
        }
        cur++;
        x = nxt[0][x];
 
        if(x != y) return -1;
        return cur;
    };
 
    while(q--){
        int a,b; cin >> a >> b;
        a = nw_order[a];
        b = nw_order[b];
 
        int ans = get(a,b);
        if(ans == -1) cout << "impossible\n";
        else cout << ans << '\n';
    }
}

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