제출 #1036843

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1036843		juicy	Olympic Bus (JOI20_ho_t4)	C++17	0 / 100	95 ms	3932 KiB

ho_t4

#include <bits/stdc++.h>
 
using namespace std;
 
#ifdef LOCAL
#include "debug.h"
#else
#define debug(...) 42
#endif
 
const int N = 205, M = 5e4 + 5;
const int inf = 1e9;
 
int n, m;
int pr[N], w[M], d[2][N];
array<int, 2> f[N];
bool spec[M];
vector<array<int, 2>> g[N], rg[N];
array<int, 3> edges[M];
 
void dijkstra(int s, int *d) {
  using T = array<int, 2>;
  priority_queue<T, vector<T>, greater<T>> pq;
  fill(d + 1, d + n + 1, inf);
  fill(pr + 1, pr + n + 1, 0);
  pq.push({d[s] = 0, s});
  while (pq.size()) {
    auto [c, u] = pq.top(); pq.pop();
    if (c != d[u]) {
      continue;
    }
    for (auto [v, id] : g[u]) {
      if (d[v] > d[u] + w[id]) {
        pr[v] = id;
        pq.push({d[v] = d[u] + w[id], v});
      }
    }
  }
}

void mark() {
  for (int i = 1; i <= n; ++i) {
    spec[pr[i]] = 1;
  }
}
 
void solve(int src) {
  fill(f + 1, f + n + 1, array<int, 2>{inf, inf});
  using T = array<int, 3>;
  priority_queue<T, vector<T>, greater<T>> pq;
  pq.push({f[src][0] = 0, src, 0});
  while (pq.size()) {
    auto [c, u, type] = pq.top(); pq.pop();
    if (f[u][type] != c) {
      continue;
    }
    for (auto [v, id] : g[u]) {
      if (!spec[id] && f[v][type] > c + w[id]) {
        pq.push({f[v][type] = c + w[id], v, type});
      }
    }
    if (!type) {
      for (auto [v, id] : rg[u]) {
        if (!spec[id] && f[v][1] > c + w[id] + edges[id][2]) {
          pq.push({f[v][1] = c + w[id] + edges[id][2], v, 1});
        }
      }
    } 
  }
}

int main() {
  ios::sync_with_stdio(false); cin.tie(nullptr);
 
  cin >> n >> m;
  for (int i = 1; i <= m; ++i) {
    int u, v, c; cin >> u >> v >> w[i] >> c;
    edges[i] = {u, v, c};
    g[u].push_back({v, i});
    rg[v].push_back({u, i});
  }
  dijkstra(1, d[0]);
  mark();
  dijkstra(n, d[1]);
  mark();
  auto del = [&](int u, array<int, 2> x) {
    for (auto &v : g[u]) {
      if (v == x) {
        swap(v, g[u].back());
        g[u].pop_back();
        break;
      }
    }
  };
  auto add = [&](int u, array<int, 2> x) {
    g[u].push_back(x);
  };
  int res = 2 * inf;
  if (d[0][n] != inf && d[1][1] != inf) {
    res = d[0][n] + d[1][1];
  }
  solve(1);
  if (d[1][1] != inf && f[n][1] != inf) {
    res = min(res, d[1][1] + f[n][1]);
  }
  solve(n);
  if (d[0][n] != inf && f[1][1] != inf) {
    res = min(res, d[0][n] + f[1][1]);
  }
  for (int i = 1; i <= m; ++i) {
    if (spec[i]) {
      auto [u, v, c] = edges[i];
      del(u, {v, i});
      add(v, {u, i});
      dijkstra(1, d[0]);
      dijkstra(n, d[1]);
      if (d[0][n] != inf && d[1][1] != inf) {
        res = min(res, d[0][n] + d[1][1] + c);
      }
      del(v, {u, i});
      add(u, {v, i});
    }
  }
  cout << (res != 2 * inf ? res : -1);
  return 0;
}

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