Submission #1049500

#	Time	Username	Problem	Language	Result	Execution time	Memory
1049500		avighna	Relay Marathon (NOI20_relaymarathon)	C++17	17 / 100	4455 ms	1048576 KiB

RelayMarathon

#include <bits/stdc++.h>

typedef long long ll;

const ll inf = 1e15;

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

  ll n, m, k;
  std::cin >> n >> m >> k;
  std::vector<std::vector<std::pair<ll, ll>>> adj(n + 1);
  for (ll i = 0, u, v, w; i < m; ++i) {
    std::cin >> u >> v >> w;
    adj[u].push_back({v, w});
    adj[v].push_back({u, w});
  }
  std::vector<ll> A(k);
  std::vector<bool> special(n + 1);
  for (auto &i : A) {
    std::cin >> i;
    special[i] = true;
  }

  auto sssp = [&](ll x) {
    std::priority_queue<std::pair<ll, ll>> pq;
    pq.push({0, x});
    std::vector<ll> ans(n + 1, inf);
    std::vector<bool> vis(n + 1);
    ans[x] = 0;
    while (!pq.empty()) {
      ll node = pq.top().second, d = -pq.top().first;
      pq.pop();
      if (vis[node]) {
        continue;
      }
      vis[node] = true;
      for (auto &[i, dist] : adj[node]) {
        if (d + dist < ans[i]) {
          ans[i] = d + dist;
          pq.push({-ans[i], i});
        }
      }
    }
    return ans;
  };

  std::vector<std::vector<ll>> dist(n + 1);
  std::vector<std::vector<std::pair<ll, ll>>> sorted_dists(n + 1);
  for (ll i = 1; i <= n; ++i) {
    dist[i] = sssp(i);
    for (ll j = 1; j <= n; ++j) {
      if (i == j or !special[j]) {
        continue;
      }
      sorted_dists[i].push_back({dist[i][j], j});
    }
    std::sort(sorted_dists[i].begin(), sorted_dists[i].end());
  }

  ll ans = inf;
  for (ll p_a = 0; p_a < k; ++p_a) {
    for (ll p_b = p_a + 1; p_b < k; ++p_b) {
      for (ll p_c = p_b + 1; p_c < k; ++p_c) {
        ll a = A[p_a], b = A[p_b], c = A[p_c];
        ll ptr = 0;
        while (ptr < sorted_dists[c].size() and
               (sorted_dists[c][ptr].second == a or
                sorted_dists[c][ptr].second == b)) {
          ptr++;
        }
        if (ptr < sorted_dists[c].size()) {
          ans = std::min(ans, dist[a][b] + sorted_dists[c][ptr].first);
        }
      }
    }
  }
  std::cout << ans << '\n';
}

Compilation message (stderr)

RelayMarathon.cpp: In function 'int main()':
RelayMarathon.cpp:68:20: warning: comparison of integer expressions of different signedness: 'll' {aka 'long long int'} and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   68 |         while (ptr < sorted_dists[c].size() and
      |                ~~~~^~~~~~~~~~~~~~~~~~~~~~~~
RelayMarathon.cpp:73:17: warning: comparison of integer expressions of different signedness: 'll' {aka 'long long int'} and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   73 |         if (ptr < sorted_dists[c].size()) {
      |             ~~~~^~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 12 / 12
• Subtask 3: 0 / 25
• Subtask 4: 0 / 58