Submission #1245771

#	Time	Username	Problem	Language	Result	Execution time	Memory
1245771		bncodero_o123	Cities (BOI16_cities)	C++20	100 / 100	1519 ms	39724 KiB

cities

#include <bits/stdc++.h>
#define pii pair<int, int>
#define ll long long
#define name "code"
using namespace std;

const int max_n= 1e5;
int n, m, k, a[max_n + 2];
vector<pii> adj[max_n + 2];

const ll inf= 1e16;
ll dp[35][max_n + 2];

void upd(int mask) {
    priority_queue<pair<ll, int>> pq;
    for(int i= 1; i <= n; ++i)
        if(dp[mask][i] != inf) pq.push(make_pair(-dp[mask][i], i));

    while(pq.size()) {
        auto [dis, u]= pq.top(); pq.pop();
        dis= -dis;
        if(dis != dp[mask][u]) continue;

        for(auto [v, w] : adj[u])
            if(dp[mask][v] > dp[mask][u] + w) {
                dp[mask][v]= dp[mask][u] + w;
                pq.push(make_pair(-dp[mask][v], v));
            }
    }
}

void solve() {
    cin >> n >> k >> m;
    for(int i= 0; i < k; ++i) cin >> a[i];
    for(int i= 0; i < m; ++i) {
        int u, v, w; cin >> u >> v >> w;
        adj[u].push_back(make_pair(v, w));
        adj[v].push_back(make_pair(u, w));
    }

    for(int i= 1; i < (1 << k); ++i)
        for(int j= 1; j <= n; ++j)
            dp[i][j]= inf;
    for(int i= 0; i < k; ++i) dp[1 << i][a[i]]= 0;

    for(int mask= 1; mask < (1 << k); ++mask) {
        for(int i= 1; i <= n; ++i)
            for(int sub= mask - 1; sub > 0; sub= (sub - 1) & mask)
                dp[mask][i]= min(dp[mask][i], dp[sub][i] + dp[mask ^ sub][i]);
        upd(mask);
    }

    ll ans= inf;
    for(int i= 1; i <= n; ++i) ans= min(ans, dp[(1 << k) - 1][i]);
    cout << ans << '\n';
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(NULL);
    if(fopen(name".inp", "r")) {
        freopen(name".inp", "r", stdin);
        freopen(name".out", "w", stdout);
    }

    int T= 1;
    for(; T; --T) solve();

    return 0;
}

Compilation message (stderr)

cities.cpp: In function 'int main()':
cities.cpp:62:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   62 |         freopen(name".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
cities.cpp:63:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   63 |         freopen(name".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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