Submission #573031

#	Time	Username	Problem	Language	Result	Execution time	Memory
573031		MohamedFaresNebili	Event Hopping (BOI22_events)	C++14	0 / 100	78 ms	13324 KiB

events

#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 all(x) (x).begin(), (x).end()

        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];
        vector<pair<ii, int>> arr;
        int lb(int v) {
            int lo = 0, hi = N - 1, res = N;
            while(lo <= hi) {
                int md = (lo + hi) / 2;
                if(arr[md].ff.ff <= v)
                    res = md, lo = md + 1;
                else hi = md - 1;
            }
            return res;
        }

        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];
                arr.pb({{S[l], E[l]}, l});
            }
            sort(all(arr));
            for(int l = 1; l <= N; l++) {
                int i = lb(E[l]);
                for(; i < N; i++) {
                    int s = arr[i].ff.ff, e = arr[i].ff.ss, d = arr[i].ss;
                    if(E[l] >= s && E[l] <= e)
                        adj[l].pb(i);
                    else if(E[l] < s) break;
                }
            }
            vector<ii> query[N + 1]; int ans[Q];
            for(int l = 0; l < Q; l++) {
                int U, V; cin >> U >> V;
                query[U].pb({V, l});
            }
            for(int U = 1; U <= N; U++) {
                if(!query[U].size()) continue;
                vector<int> D(N + 1, -1);
                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] != -1) continue;
                        D[u] = D[A] + 1; q.push(u);
                    }
                }
                for(auto V : query[U])
                    ans[V.ss] = D[V.ff];
            }
            for(int l = 0; l < Q; l++) {
                if(ans[l] == -1) cout << "impossible\n";
                else cout << ans[l] << "\n";
            }
        }

Compilation message (stderr)

events.cpp: In function 'int32_t main()':
events.cpp:45:61: warning: unused variable 'd' [-Wunused-variable]
   45 |                     int s = arr[i].ff.ff, e = arr[i].ff.ss, d = arr[i].ss;
      |                                                             ^

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