Submission #745929

#	Time	Username	Problem	Language	Result	Execution time	Memory
745929		vjudge1	Cities (BOI16_cities)	C++17	15 / 100	6071 ms	136796 KiB

cities

#include <algorithm>
#include <climits>
#include <iostream>
#include <queue>
#include <vector>

using namespace std;

using ll = long long;

struct edge {
    int to;
    ll weight;

    bool operator >(edge const& rhs) const {
        return weight > rhs.weight;
    }
};

vector<ll> dijkstra(vector<vector<edge>> const& graph, int const start) {
    priority_queue<edge, vector<edge>, greater<edge>> pq;
    vector<ll> dist(graph.size(), LLONG_MAX / 3);

    dist[start] = 0;
    pq.push({ start, 0 });

    while (!pq.empty()) {
        auto const [cur, cur_dist] = pq.top();
        pq.pop();

        if (cur_dist != dist[cur])
            continue;

        for (auto const& [neigh, weight] : graph[cur]) {
            ll const new_dist = cur_dist + weight;

            if (new_dist < dist[neigh]) {
                dist[neigh] = new_dist;
                pq.push({ neigh, new_dist });
            }
        }
    }

    return dist;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int n, k, m;
    cin >> n >> k >> m;

    vector<int> important(k);

    for (int& x : important) {
        cin >> x;
        x--;
    }
    

    vector<vector<edge>> graph(n);

    for (int i = 0; i < m; i++) {
        int u, v;
        ll w;
        cin >> u >> v >> w;
        u--; v--;
        
        graph[u].push_back({ v, w });
        graph[v].push_back({ u, w });
    }

    vector<vector<ll>> dist(n);

    for (int i = 0; i < n; i++)
        dist[i] = dijkstra(graph, i);
    
    ll min_dist = LLONG_MAX / 3;

    for (int a = 0; a < n - 1; a++) {
        for (int b = a + 1; b < n; b++) {
            ll cur_dist = dist[a][b];

            for (int const& i : important) {
                cur_dist += min(dist[a][i], dist[b][i]);
            }

            min_dist = min(min_dist, cur_dist);
        }
    }

    cout << min_dist << "\n";
}

• Subtask 1: 0 / 22
• Subtask 2: 0 / 14
• Subtask 3: 15 / 15
• Subtask 4: 0 / 23
• Subtask 5: 0 / 26