제출 #572894

#제출 시각아이디문제언어결과실행 시간메모리
572894MohamedFaresNebiliEvent Hopping (BOI22_events)C++14
10 / 100
1577 ms57356 KiB
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>

        using namespace std;
        using namespace __gnu_pbds;

        using ll = long long;
        using ii = pair<int, int>;
        using vi = vector<int>;

        #define pb push_back
        #define pp pop_back
        #define ff first
        #define ss second
        #define lb lower_bound
        #define int ll

        typedef tree<int, null_type, less<int>, rb_tree_tag,
            tree_order_statistics_node_update> indexed_set;

        int N, Q; int S[100001], E[100001];
        vector<int> adj[100001];

        int32_t main() {
            ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
            cin >> N >> Q;
            for(int l = 1; l <= N; l++)
                cin >> S[l] >> E[l];
            for(int l = 1; l <= N; l++) {
                for(int i = 1; i <= N; i++) {
                    if(l == i) continue;
                    if(E[l] >= S[i] && E[l] <= E[i])
                        adj[l].pb(i);
                }
            }
            while(Q--) {
                int U, V; cin >> U >> V;
                vector<int> D(N + 1, 1e9 + 7);
                queue<int> q; q.push(U); D[U] = 0;
                while(!q.empty()) {
                    int A = q.front(); q.pop();
                    for(auto u : adj[A]) {
                        if(D[u] != 1e9 + 7) continue;
                        D[u] = D[A] + 1; q.push(u);
                    }
                }
                if(D[V] ==  1e9 + 7) cout << "impossible\n";
                else cout << D[V] << "\n";
            }
        }























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