Submission #392888

#	Time	Username	Problem	Language	Result	Execution time	Memory
392888		arujbansal	Cities (BOI16_cities)	C++17	100 / 100	2546 ms	49660 KiB

cities

#include <iostream>
#include <algorithm>
#include <vector>
#include <map>
#include <set>
#include <array>
#include <stack>
#include <queue>
#include <random>
#include <numeric>
#include <functional>
#include <chrono>
#include <utility>
#include <iomanip>
#include <assert.h>

using namespace std;

void dbg_out() { cerr << endl; }
template<typename Head, typename... Tail>
void dbg_out(Head H, Tail... T) { cerr << ' ' << H; dbg_out(T...); }
#define dbg(...) cerr << "(" << #__VA_ARGS__ << "):", dbg_out(__VA_ARGS__)

#define rng_init mt19937 rng(chrono::steady_clock::now().time_since_epoch().count())
#define rng_seed(x) mt19937 rng(x)
#define all(x) (x).begin(), (x).end()
#define sz(x) (int) (x).size()
#define int long long

const int MXN = 1e5 + 5, INF = 1e18;
int N, M, K;
vector<pair<int, int>> g[MXN];
vector<int> important;
int dp[(1 << 5)][MXN], dist[MXN];

void run_dijkstra(int mask) {
    priority_queue<pair<int, int>, vector<pair<int, int>>, greater<>> pq;

    for (int v = 0; v < N; v++) {
        pq.emplace(dp[mask][v], v);
        dist[v] = dp[mask][v];
    }

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

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

        for (const auto &[v, w] : g[u]) {
            int new_dist = cur_dist + w;

            if (new_dist < dist[v]) {
                dist[v] = new_dist;
                pq.emplace(new_dist, v);
            }
        }
    }

    for (int v = 0; v < N; v++)
        dp[mask][v] = dist[v];
}

void solve() {
    cin >> N >> K >> M;

    important.resize(K);
    for (auto &x : important) {
        cin >> x;
        x--;
    }

    for (int i = 0; i < M; i++) {
        int u, v, w;
        cin >> u >> v >> w;
        u--, v--;

        g[u].emplace_back(v, w);
        g[v].emplace_back(u, w);
    }

    for (int i = 0; i < (1 << K); i++)
        for (int j = 0; j < N; j++)
            dp[i][j] = INF;

    for (int i = 0; i < K; i++)
        dp[1 << i][important[i]] = 0;

    for (int mask = 0; mask < (1 << K); mask++) {
        for (int v = 0; v < N; v++)
            for (int submask = mask; submask > 0; submask = (submask - 1) & mask)
                dp[mask][v] = min(dp[mask][v], dp[submask][v] + dp[mask ^ submask][v]);

        run_dijkstra(mask);
    }

    int ans = INF;
    for (int v = 0; v < N; v++)
        ans = min(ans, dp[(1 << K) - 1][v]);

    cout << ans;
}

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

    int TC = 1;
    // cin >> TC;
    while (TC--) solve();
}

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