Submission #392871

#	Time	Username	Problem	Language	Result	Execution time	Memory
392871		arujbansal	Cities (BOI16_cities)	C++17	0 / 100	227 ms	35436 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

struct UFDS {
    int n;
    vector<int> info;
 
    UFDS() {}
 
    UFDS(int _n) { init(_n); }
 
    void init(int _n) {
        n = _n;
        info.assign(n, -1);
    }
 
    int get(int x) {
        if (info[x] < 0) return x;
        return info[x] = get(info[x]);
    }
 
    bool unite(int x, int y) {
        x = get(x), y = get(y);
        if (x == y) return false;
 
        if (info[x] > info[y])
            swap(x, y);
 
        info[x] += info[y];
        info[y] = x;
 
        return true;    
    }
 
    bool connected(int x, int y) { return get(x) == get(y); }
};

struct Edge {
    int u, v, w;

    Edge(int u, int v, int w) : u(u), v(v), w(w) {}

    bool operator<(const Edge &other) const {
        return w < other.w;
    }
};

const int MXN = 1e5 + 5, INF = 1e18;

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

    vector<int> dist(N, INF), par(N, -1);
    priority_queue<pair<int, int>, vector<pair<int, int>>, greater<>> pq;

    for (int i = 0; i < K; i++) {
        int v;
        cin >> v;
        v--;

        dist[v] = 0;
        par[v] = v;

        pq.emplace(0, v);
    }

    vector<Edge> edges;

    vector<pair<int, int>> g[N];
    for (int i = 0; i < M; i++) {
        int u, v, w;
        cin >> u >> v >> w;
        u--, v--;

        edges.emplace_back(u, v, w);

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

    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;
                par[v] = par[u];

                pq.emplace(new_dist, v);
            }
        }
    }

    vector<Edge> kruskals;

    for (const auto &[u, v, w] : edges) {
        if (par[u] != par[v]) {
            kruskals.emplace_back(par[u], u, dist[u]);
            kruskals.emplace_back(par[v], v, dist[v]);
            kruskals.emplace_back(u, v, w);
        }
    }

    sort(all(kruskals));

    UFDS ufds(N);

    int cost = 0;
    for (const auto &[u, v, w] : kruskals) {
        if (ufds.unite(u, v))
            cost += w;
    }

    cout << cost;
}

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

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

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