Submission #1183673

#	Time	Username	Problem	Language	Result	Execution time	Memory
1183673		meicris	Toll (BOI17_toll)	C++17	18 / 100	3106 ms	576672 KiB

toll

#include <iostream>
#include <vector>
#include <queue>
#include <unordered_map>
#include <climits>
using namespace std;
const int INF = 1e9;
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int K, N, M, O;
    cin >> K >> N >> M >> O;
    vector<vector<pair<int, int>>> graph(N);
    for (int i = 0; i < M; ++i) {
        int a, b, c;
        cin >> a >> b >> c;
        if (b / K == a / K + 1) {
            graph[a].emplace_back(b, c);
        }
    }
    vector<pair<int, int>> orders(O);
    unordered_map<int, vector<int>> orders_by_origin;
    for (int i = 0; i < O; ++i) {
        int a, b;
        cin >> a >> b;
        orders[i] = {a, b};
        orders_by_origin[a].push_back(i);
    }
    auto dijkstra = [&](int start) -> vector<int> {
        vector<int> dist(N, INF);
        priority_queue<pair<int, int>, vector<pair<int, int>>, greater<>> pq;
        dist[start] = 0;
        pq.emplace(0, start);
        while (!pq.empty()) {
            auto [d, u] = pq.top();
            pq.pop();
            if (d > dist[u]) continue;
            for (auto &[v, cost] : graph[u]) {
                if (dist[v] > dist[u] + cost) {
                    dist[v] = dist[u] + cost;
                    pq.emplace(dist[v], v);
                }
            }
        }

        return dist;
    };
    vector<int> answers(O, -1);
    unordered_map<int, vector<int>> dist_cache;
    for (auto &[origin, order_indices] : orders_by_origin) {
        if (dist_cache.find(origin) == dist_cache.end()) {
            dist_cache[origin] = dijkstra(origin);
        }
        vector<int>& dist_from_origin = dist_cache[origin];
        for (int idx : order_indices) {
            int a = orders[idx].first;
            int b = orders[idx].second;
            if (dist_from_origin[b] < INF) {
                answers[idx] = dist_from_origin[b];
            }
        }
    }
    for (int ans : answers) {
        cout << ans << '\n';
    }

    return 0;
}

• Subtask 1: 0 / 7
• Subtask 2: 10 / 10
• Subtask 3: 8 / 8
• Subtask 4: 0 / 31
• Subtask 5: 0 / 44