Submission #897915

#	Time	Username	Problem	Language	Result	Execution time	Memory
897915		avighna	Olympic Bus (JOI20_ho_t4)	C++17	5 / 100	1074 ms	5468 KiB

ho_t4

#include <bits/stdc++.h>

using namespace std;

#define ll long long

const ll N = 201, M = 50001;

ll n, m;

multiset<pair<ll, ll>> adj[N];
ll c[M], d[M];
pair<ll, ll> edges[M];

vector<ll> sssp(ll source) {
  vector<ll> dist(n + 1, 1e15);
  dist[source] = 0;
  priority_queue<pair<ll, ll>> pq;
  pq.push({0, source});
  while (!pq.empty()) {
    ll node = pq.top().second, _dist = -pq.top().first;
    pq.pop();
    for (auto &nb : adj[node]) {
      if (dist[nb.first] > _dist + c[nb.second]) {
        dist[nb.first] = _dist + c[nb.second];
        pq.push({-dist[nb.first], nb.first});
      }
    }
  }
  return dist;
}

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

  cin >> n >> m;
  for (ll i = 1; i <= n; ++i) {
    adj[i].clear();
  }
  vector<vector<ll>> dist(n + 1, vector<ll>(n + 1, 1e15));
  for (ll i = 1; i <= n; ++i) {
    dist[i][i] = 0;
  }
  for (ll i = 0, u, v; i < m; ++i) {
    cin >> u >> v >> c[i] >> d[i];
    adj[u].insert({v, i});
    edges[i] = {u, v};
    dist[u][v] = min(dist[u][v], c[i]);
  }

  for (ll a = 1; a <= n; ++a) {
    for (ll b = 1; b <= n; ++b) {
      for (ll c = 1; c <= n; ++c) {
        dist[a][c] = min(dist[a][c], dist[a][b] + dist[b][c]);
      }
    }
  }

  ll ans = 1e15;
  ans = min(ans, sssp(1)[n] + sssp(n)[1]);
  for (ll i = 0; i < m; ++i) {
    adj[edges[i].first].erase(adj[edges[i].first].find({edges[i].second, i}));
    adj[edges[i].second].insert({edges[i].first, i});
    ans = min(ans, d[i] + sssp(1)[n] + sssp(n)[1]);
    adj[edges[i].second].erase(adj[edges[i].second].find({edges[i].first, i}));
    adj[edges[i].first].insert({edges[i].second, i});
  }
  if (ans == (ll)(1e15)) {
    ans = -1;
  }
  cout << ans << "\n";
}

• Subtask 1: 5 / 5
• Subtask 2: 0 / 11
• Subtask 3: 0 / 21
• Subtask 4: 0 / 63