Submission #889865

#	Time	Username	Problem	Language	Result	Execution time	Memory
889865		CDuong	Relay Marathon (NOI20_relaymarathon)	C++17	100 / 100	1220 ms	125956 KiB

RelayMarathon

/*
#pragma GCC optimize("Ofast,unroll-loops")
#pragma GCC target("avx2,fma,bmi,bmi2,sse4.2,popcnt,lzcnt")
*/

#include <bits/stdc++.h>
#define taskname ""
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define i64 long long
#define pb push_back
#define ff first
#define ss second
#define isz(x) (int)x.size()
using namespace std;

const int mxN = 1e5 + 5;
const int mod = 1e9 + 7;
const i64 oo = 1e18;

int n, m, k;
bool marked[mxN];
vector<pair<int, int>> G[mxN];

pair<int, int> dijkstra_with_starting_point(int st) {
    vector<int> dis(n + 1, 1e9);
    priority_queue<pair<int, int>> pq;
    pq.emplace(0, st); dis[st] = 0;
    while (not pq.empty()) {
        int v = pq.top().ss;
        int cdis = -pq.top().ff;
        pq.pop();
        if (marked[v]) return {cdis, v};
        if (cdis != dis[v]) continue;
        for (auto [u, w] : G[v]) {
            if (cdis + w < dis[u]) {
                dis[u] = cdis + w;
                pq.emplace(-dis[u], u);
            }
        }
    }
    return {1e9, -1};
}

pair<int, pair<int, int>> dijkstra_without_starting_point() {
    vector<int> src(n + 1, 0);
    vector<int> dis(n + 1, 1e9);
    priority_queue<pair<int, int>> pq;
    for (int i = 1; i <= n; ++i) if (marked[i]) {
        pq.emplace(0, i);
        dis[i] = 0, src[i] = i;
    }
    while (not pq.empty()) {
        int v = pq.top().ss;
        int cdis = -pq.top().ff;
        pq.pop();
        if (cdis != dis[v]) continue;
        for (auto [u, w] : G[v]) {
            if (cdis + w < dis[u]) {
                src[u] = src[v];
                dis[u] = cdis + w;
                pq.emplace(-dis[u], u);
            }
        }
    }
    int res = 1e9, ru = -1, rv = -1;
    for (int i = 1; i <= n; ++i) for (auto [u, w] : G[i]) {
        if (src[i] != src[u] && dis[u] + dis[i] + w < res)
            res = dis[u] + dis[i] + w, ru = src[i], rv = src[u];
    }
    return {res, {ru, rv}};
}

void solve() {
    cin >> n >> m >> k;
    for (int i = 1; i <= m; ++i) {
        int u, v, w;
        cin >> u >> v >> w;
        G[u].emplace_back(v, w);
        G[v].emplace_back(u, w);
    }
    for (int i = 1; i <= k; ++i) {
        int idx; cin >> idx;
        marked[idx] = true;
    }

   int res = 1e9;
   auto tmp = dijkstra_without_starting_point();
   int s = tmp.ss.ff, t = tmp.ss.ss, dis1 = tmp.ff;
   marked[s] = marked[t] = false;
   tmp = dijkstra_without_starting_point();
   res = min(res, dis1 + tmp.ff);

   auto tmp1 = dijkstra_with_starting_point(s);
   dis1 = tmp1.ff, marked[tmp1.ss] = false;
   res = min(res, dis1 + dijkstra_with_starting_point(t).ff);
   marked[tmp1.ss] = true;

   auto tmp2 = dijkstra_with_starting_point(t);
   dis1 = tmp2.ff, marked[tmp2.ss] = false;
   res = min(res, dis1 + dijkstra_with_starting_point(s).ff);
   marked[tmp2.ss] = false;

   cout << res << endl;
}

signed main() {

#ifndef CDuongg
    if(fopen(taskname".inp", "r"))
        assert(freopen(taskname".inp", "r", stdin)), assert(freopen(taskname".out", "w", stdout));
#else
    freopen("bai3.inp", "r", stdin);
    freopen("bai3.out", "w", stdout);
    auto start = chrono::high_resolution_clock::now();
#endif

    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int t = 1; //cin >> t;
    while(t--) solve();

#ifdef CDuongg
   auto end = chrono::high_resolution_clock::now();
   cout << "\n"; for(int i = 1; i <= 100; ++i) cout << '=';
   cout << "\nExecution time: " << chrono::duration_cast<chrono::milliseconds> (end - start).count() << "[ms]" << endl;
   cout << "Check array size pls sir" << endl;
#endif

}

• Subtask 1: 5 / 5
• Subtask 2: 12 / 12
• Subtask 3: 25 / 25
• Subtask 4: 58 / 58