Submission #1106347

#	Time	Username	Problem	Language	Result	Execution time	Memory
1106347		Zero_OP	Cities (BOI16_cities)	C++14	74 / 100	6070 ms	172864 KiB

cities

#include <bits/stdc++.h>

using namespace std;

template<typename T>
    bool minimize(T& a, const T& b){
        if(a > b){
            return a = b, true;
        } return false;
    }

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    int N, K, M;
    cin >> N >> K >> M;
    vector<int> cities(K);
    for(int i = 0; i < K; ++i){
        cin >> cities[i];
        --cities[i];
    }

    vector<vector<pair<int, int>>> adj(N);
    while(M--){
        int u, v, w;
        cin >> u >> v >> w;
        --u, --v;
        adj[u].push_back({v, w});
        adj[v].push_back({u, w});
    }

    const long long inf = 1e18;
    using node = tuple<long long, int, int>;
    priority_queue<node, vector<node>, greater<node>> pq;
    vector<vector<long long>>  d(1 << K, vector<long long>(N, inf));
    vector<vector<bool>> visited(1 << K, vector<bool>(N, false));

    for(int i = 0; i < K; ++i){
        d[1 << i][cities[i]] = 0;
        pq.push({d[1 << i][cities[i]], 1 << i, cities[i]});
    }

    auto mergeMask = [&](int u){
        for(int mask = 1; mask < (1 << K); ++mask){
            if(!visited[mask][u]){
                for(int s = mask - 1 & (mask); s > 0; s = (s - 1) & (mask)){
                    if(minimize(d[mask][u], d[s][u] + d[mask ^ s][u])){
                        pq.push({d[mask][u], mask, u});
                    }
                }
            }
        }
    };

    while(!pq.empty()){
        long long cur; int mask, u;
        tie(cur, mask, u) = pq.top(); pq.pop();

        if(visited[mask][u]) continue;
        visited[mask][u] = true;

        mergeMask(u);
        for(auto [v, w] : adj[u]){
            if(minimize(d[mask][v], d[mask][u] + w)){
                pq.push({d[mask][v], mask, v});
            }
        }
    }

    long long ans = inf;
    for(int i = 0; i < N; ++i){
        minimize(ans, d[(1 << K) - 1][i]);
    }
    cout << ans << '\n';

    return 0;
}

Compilation message (stderr)

cities.cpp: In lambda function:
cities.cpp:47:34: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
   47 |                 for(int s = mask - 1 & (mask); s > 0; s = (s - 1) & (mask)){
      |                             ~~~~~^~~
cities.cpp: In function 'int main()':
cities.cpp:64:18: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   64 |         for(auto [v, w] : adj[u]){
      |                  ^

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