제출 #244953

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
244953		rama_pang	Olympic Bus (JOI20_ho_t4)	C++14	100 / 100	507 ms	3828 KiB

ho_t4

#include <bits/stdc++.h>
using namespace std;

const int MAXN = 205;
const int MAXM = 50005;

int N, M;
vector<int> adj[MAXN];
vector<int> radj[MAXN];
vector<array<int, 4>> edge;

int par[5][MAXN];
int dist[5][MAXN];
int sptree[5][MAXM];

void DijkstraSparse(int s, int k, vector<int> a[MAXN]) {
  for (int i = 0; i < MAXN; i++) {
    dist[k][i] = 2e9;
  }
  priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> pq;
  pq.emplace(0, s);
  auto dt = dist[k];
  auto pr = par[k];
  dt[s] = 0;
  pr[s] = -1;
  while (!pq.empty()) {
    int u = pq.top().second;
    int d = pq.top().first;
    pq.pop();
    if (dt[u] != d) {
      continue;
    }
    if (pr[u] != -1) {
      sptree[k][pr[u]] = 1;
    }
    for (auto e : a[u]) {
      int v = edge[e][0] ^ edge[e][1] ^ u;
      if (dt[v] > dt[u] + edge[e][2]) {
        dt[v] = dt[u] + edge[e][2];
        pr[v] = e;
        pq.emplace(dt[v], v);
      }
    }
  }
}

int DijkstraDense(int s, int t, int block, int ru, int rv, int rc) {
  int weight[MAXN][MAXN];
  for (int i = 1; i <= N; i++) {
    dist[4][i] = 2e9;
    for (int j = 1; j <= N; j++) {
      weight[i][j] = 2e9;
    }
  }
  for (int i = 0; i < M; i++) if (i != block) {
    int u, v, c;
    u = edge[i][0], v = edge[i][1], c = edge[i][2];
    weight[u][v] = min(weight[u][v], c);
  }
  weight[ru][rv] = min(weight[ru][rv], rc);

  int vis[MAXN] = {};
  auto dt = dist[4];
  for (int i = 1; i <= N; i++) {
    dt[i] = 2e9;
  }
  dt[s] = 0;
  for (int rep = 1; rep <= N; rep++) {
    int u = -1;
    for (int i = 1; i <= N; i++) if (!vis[i]) {
      if (u == -1 || dt[u] > dt[i]) {
        u = i;
      }
    }
    if (dt[u] == 2e9) {
      break;
    }
    vis[u] = 1;
    for (int v = 1; v <= N; v++) if (weight[u][v] < 2e9) {
      dt[v] = min(dt[v], dt[u] + weight[u][v]);
    }
  }
  return dt[t];
}

int main() {
  ios::sync_with_stdio(0);
  cin.tie(0), cout.tie(0);

  cin >> N >> M;
  for (int i = 0; i < M; i++) {
    int u, v, c, d;
    cin >> u >> v >> c >> d;
    edge.push_back({u, v, c, d});
    adj[u].emplace_back(i);
    radj[v].emplace_back(i);
  }

  DijkstraSparse(1, 0, adj); // 1 to N
  DijkstraSparse(N, 1, adj); // N to 1
  DijkstraSparse(N, 2, radj); // 1 to N, reverse
  DijkstraSparse(1, 3, radj); // N to 1, reverse

  int ans = (int) min((long long) 2e9, 1ll * dist[0][N] + 1ll * dist[1][1]);
  for (int i = 0; i < M; i++) {
    int u, v, c, d;
    u = edge[i][0], v = edge[i][1], c = edge[i][2], d = edge[i][3];
    if (sptree[0][i] == 0 && sptree[1][i] == 0) {
      int d1 = min((long long) dist[0][N], (long long) dist[0][v] + c + dist[2][u]);
      int d2 = min((long long) dist[1][1], (long long) dist[1][v] + c + dist[3][u]);
      if (d1 < 2e9 && d2 < 2e9) {
        ans = min(ans, d + d1 + d2);
      }
    } else {
      int d1 = DijkstraDense(1, N, i, v, u, c);
      int d2 = DijkstraDense(N, 1, i, v, u, c);
      if (d1 < 2e9 && d2 < 2e9) {
        ans = min(ans, d + d1 + d2);
      }
    }
  }
  if (ans >= 2e9) {
    ans = -1;
  }
  cout << ans << "\n";
  return 0;
}

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