Submission #889879

#	Time	Username	Problem	Language	Result	Execution time	Memory
889879		shivensinha4	Passport (JOI23_passport)	C++17	48 / 100	2155 ms	907608 KiB

passport

#include "bits/stdc++.h"
#ifdef mlocal
#include "./Competitive-Code-Library/snippets/prettyprint.h"
#endif
using namespace std;
#define for_(i, s, e) for (int i = s; i < (int) e; i++)
#define for__(i, s, e) for (ll i = s; i < e; i++)
typedef long long ll;
typedef vector<int> vi;
typedef array<int, 2> ii;
#define endl '\n'

const int INF = 1e9, BS = 400;

int main() {
#ifdef mlocal
    freopen("test.in", "r", stdin);
#endif

    ios_base::sync_with_stdio(false);
    cin.tie(0);

    int n; cin >> n;
    const int blocks = (n + BS - 1) / BS;
    vector<ii> seg(n);
    vector<vi> can_reach(n), can_reach_b(blocks);
    for_(i, 0, n){
        cin >> seg[i][0] >> seg[i][1], seg[i][0]--, seg[i][1]--;

        int pt = seg[i][0];
        while (pt % BS != 0 and pt <= seg[i][1]) {
            can_reach[pt].push_back(i);
            pt++;
        }
        while (pt + BS <= seg[i][1]) {
            can_reach_b[pt / BS].push_back(i);
            pt += BS;
        }
        while (pt <= seg[i][1]) {
            can_reach[pt].push_back(i);
            pt++;
        }
    }

    function<vi(int)> bfs = [&] (int s) {
        vi dist(n, INF);
        auto cr = can_reach, crb = can_reach_b;

        dist[s] = 0;
        queue<int> q;
        q.push(s);
        while (q.size()) {
            auto p = q.front(); q.pop();
            for (auto i: cr[p]) if (dist[i] == INF) {
                dist[i] = dist[p] + 1;
                q.push(i);
            }
            for (auto i: crb[p / BS]) {
                if (dist[i] == INF) {
                    dist[i] = dist[p] + 1;
                    q.push(i);
                }
            }
            crb[p / BS].clear();
        }
        return dist;
    };

    vi ans = bfs(0);
    {
        vi ans2 = bfs(n - 1);
        for_(i, 0, n) ans[i] += ans2[i];
    }
    for_(i, 1, n - 1) if (ans[i] < INF) ans[i]--;

    priority_queue<ii, vector<ii>, greater<ii>> pq;
    for_(i, 0, n) pq.push({ans[i], i});
    while (pq.size()) {
        auto [dist, p] = pq.top(); pq.pop();
        if (dist != ans[p]) continue;
        for (auto i: can_reach[p]) {
            if (ans[i] > ans[p] + 1) {
                ans[i] = ans[p] + 1;
                pq.push({ans[i], i});
            }
        }
        for (auto i: can_reach_b[p / BS]) {
            if (ans[i] > ans[p] + 1) {
                ans[i] = ans[p] + 1;
                pq.push({ans[i], i});
            }
        }
        can_reach_b[p / BS].clear();
    }

    int q; cin >> q;
    while (q--) {
        int p; cin >> p;
        p--;

        cout << (ans[p] >= INF ? -1 : ans[p]) << endl;
    }
}

• Subtask 1: 0 / 6
• Subtask 2: 16 / 16
• Subtask 3: 24 / 24
• Subtask 4: 8 / 8
• Subtask 5: 0 / 46