Submission #897966

#	Time	Username	Problem	Language	Result	Execution time	Memory
897966		avighna	Olympic Bus (JOI20_ho_t4)	C++17	37 / 100	1027 ms	6748 KiB

ho_t4

#pragma GCC optimize("O3")

#include <iostream>
#include <queue>
#include <vector>

using namespace std;

#define ll long long

const ll N = 201, M = 50001;

ll n, m;

struct Edge {
  ll u, v, i, c;
};

vector<pair<ll, pair<ll, bool>>> adj[N];
ll c[M], d[M];
Edge edges[M];

ll sssp(ll source, ll i, ll dest) {
  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();
    if (node == dest) {
      return dist[node];
    }
    for (auto &nb : adj[node]) {
      if (nb.second.second) {
        if (nb.second.first != i) {
          continue;
        }
      } else if (nb.second.first == i) {
        continue;
      }
      if (dist[nb.first] > _dist + c[nb.second.first]) {
        dist[nb.first] = _dist + c[nb.second.first];
        pq.push({-dist[nb.first], nb.first});
      }
    }
  }
  return dist[dest];
}

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].push_back({v, {i, 0}}), adj[v].push_back({u, {i, 1}});
    edges[i].u = u, edges[i].v = v, edges[i].i = i, edges[i].c = c[i];
    dist[u][v] = min(dist[u][v], c[i]);
  }

  for (ll k = 1; k <= n; ++k) {
    for (ll i = 1; i <= n; ++i) {
      for (ll j = 1; j <= n; ++j) {
        dist[i][j] = min(dist[i][j], dist[i][k] + dist[k][j]);
      }
    }
  }

  ll ans = min((ll)1e15, dist[1][n] + dist[n][1]);
  for (auto &[u, v, i, c] : edges) {
    ll d1 = min(dist[1][n], dist[1][v] + c + dist[u][n]);
    ll d2 = min(dist[n][1], dist[n][v] + c + dist[u][1]);
    if (d1 + d2 + d[i] < ans) {
      ll actual = d[i] + sssp(1, i, n) + sssp(n, i, 1);
      ans = min(ans, actual);
    }
  }
  if (ans == (ll)(1e15)) {
    ans = -1;
  }
  cout << ans << "\n";
}

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