Submission #897849

#	Time	Username	Problem	Language	Result	Execution time	Memory
897849		avighna	Olympic Bus (JOI20_ho_t4)	C++17	0 / 100	21 ms	3676 KiB

ho_t4

#include <bits/stdc++.h>

using namespace std;

#define ll long long

const ll N = 201, M = 50001;

ll n, m;

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

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].emplace_back(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]);
      }
    }
  }

  set<ll> edges_to, edges_from;
  // if (dist[1][n] != (ll)1e15) {
  //   for (ll node = 1; node != n;) {
  //     for (auto &nb : adj[node]) {
  //       if (c[nb.second] + dist[nb.first][n] == dist[node][n]) {
  //         edges_to.insert(nb.second);
  //         node = nb.first;
  //       }
  //     }
  //   }
  // }
  // if (dist[n][1] != (ll)1e15) {
  //   for (ll node = n; node != 1;) {
  //     for (auto &nb : adj[node]) {
  //       if (c[nb.second] + dist[nb.first][1] == dist[node][1]) {
  //         edges_from.insert(nb.second);
  //         node = nb.first;
  //       }
  //     }
  //   }
  // }

  ll ans = min((ll)1e15, dist[1][n] + dist[n][1]);
  for (ll i = 0; i < m; ++i) {
    ll u = edges[i].first, v = edges[i].second;
    ll _ans = d[i];
    ll d1 = dist[1][v] + c[i] + dist[u][n], d2 = dist[n][v] + c[i] + dist[u][1];
    if (1 == u || n == v) {
      d1 = 1e15;
    }
    if (u == n || 1 == v) {
      d2 = 1e15;
    }
    if (edges_to.count(i)) {
      _ans += d1;
    } else {
      _ans += min(dist[1][n], d1);
    }
    if (edges_from.count(i)) {
      _ans += d2;
    } else {
      _ans += min(dist[n][1], d2);
    }
    ans = min(ans, _ans);
  }
  if (ans == (ll)1e15) {
    ans = -1;
  }
  cout << ans << "\n";
}

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