Submission #721901

#	Time	Username	Problem	Language	Result	Execution time	Memory
721901		MDSPro	Event Hopping (BOI22_events)	C++17	10 / 100	1588 ms	30092 KiB

events

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

const int INF = 1e9;

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(y,x,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<1>(ev[i]);
        right[i] = get<0>(ev[i]);
        nw_order[get<2>(ev[i])] = i;
    }
    
    vector<vector<int>> g(n);
    for(int i = 0; i < n; ++i){
        for(int j = 0; j < n; ++j){
            if(i == j) continue;
            if(left[j] <= right[i] && right[i] <= right[j]) {
                g[i].emplace_back(j);
            }
        }
    }

    auto get = [&](int a, int b){
        if(a == b) return 0;
        vector<int> dis(n,INF); dis[a] = 0;

        queue<int> q; q.push(a);
        while(!q.empty()){
            int mn = q.front(); q.pop();
            for(int z: g[mn]){
                if(dis[z] == INF){
                    dis[z] = dis[mn]+1;
                    q.push(z);
                }
            }
        }

        if(dis[b] == INF) return -1;
        else return dis[b];
    };

    while(q--){
        int a,b; cin >> a >> b;
        a = nw_order[a];
        b = nw_order[b];

        int dis = get(a,b);
        if(dis == -1) cout << "impossible\n";
        else cout << dis << '\n';
    }
}

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