Submission #752245

#	Time	Username	Problem	Language	Result	Execution time	Memory
752245		tch1cherin	Olympic Bus (JOI20_ho_t4)	C++17	37 / 100	753 ms	25296 KiB

ho_t4

#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#define Get(x, i, j) (x[i].empty() ? x.back()[j] : x[i][j])
#include <bits/stdc++.h>
using namespace std;
 
template <typename T>
using min_heap = priority_queue<T, vector<T>, greater<T>>;
 
struct edge {
  int from, to, weight, cost, id;
 
  edge() {}
 
  edge(int _from, int _to, int _weight, int _cost, int _id) : from(_from), to(_to), weight(_weight), cost(_cost), id(_id) {}
};
 
struct node {
  int distance, parent;
 
  node() {
    distance = INT_MAX;
    parent = -1;
  }
 
  node(int _distance, int _parent) : distance(_distance), parent(_parent) {}
};

vector<node> dijkstra(vector<vector<edge>> graph, int start) {
  int n = (int)graph.size();
  vector<node> answer(n);
  min_heap<pair<int, int>> q;
  q.emplace(0, start);
  answer[start].distance = 0;
  while (!q.empty()) {
    auto [d, u] = q.top();
    q.pop();
    if (answer[u].distance > d) {
      continue;
    }
    for (auto [from, to, weight, cost, id] : graph[u]) {
      if (answer[from].distance + weight < answer[to].distance) {
        answer[to] = node(answer[from].distance + weight, id);
        q.emplace(answer[to].distance, to);
      }
    }
  }
  return answer;
}
 
vector<vector<edge>> transpose(vector<vector<edge>> graph) {
  int n = (int)graph.size();
  vector<vector<edge>> new_graph(n);
  for (int u = 0; u < n; u++) {
    for (auto [from, to, weight, cost, id] : graph[u]) {
      new_graph[to].emplace_back(to, from, weight, cost, id);
    }
  }
  return new_graph;
}
 
vector<vector<int>> find_shortest_paths_without_each_edge(vector<vector<edge>> graph, int start) {
  int n = (int)graph.size();
  int m = 0;
  for (int u = 0; u < n; u++) {
    for (auto [from, to, weight, cost, id] : graph[u]) {
      m = max(m, 1 + id);
    }
  }
  vector<node> result = dijkstra(graph, start);
  vector<int> dist(n);
  for (int i = 0; i < n; i++) {
    dist[i] = result[i].distance;
  }
  vector<vector<int>> answer(m);
  for (auto [distance, parent] : result) {
    if (parent != -1) {
      vector<vector<edge>> new_graph = graph;
      bool flag = true;
      for (int u = 0; u < n; u++) {
        for (int i = 0; i < (int)new_graph[u].size(); i++) {
          auto [from, to, weight, cost, id] = new_graph[u][i];
          if (id == parent) {
            new_graph[u].erase(new_graph[u].begin() + i);
            flag = false;
          }  
        }
      }
      vector<node> new_result = dijkstra(new_graph, start);
      answer[parent] = vector<int>(n);
      for (int i = 0; i < n; i++) {
        answer[parent][i] = new_result[i].distance;  
      }
    }
  }
  answer.push_back(dist);
  return answer;
}
 
void solve() {
  int n, m;
  cin >> n >> m;
  vector<vector<edge>> graph(n);
  for (int i = 0; i < m; i++) {
    int from, to, weight, cost;
    cin >> from >> to >> weight >> cost;
    from--, to--;
    graph[from].emplace_back(from, to, weight, cost, i);
  }
  vector<vector<edge>> rev_graph = transpose(graph);
  vector<vector<int>> result_a = find_shortest_paths_without_each_edge(graph, 0);
  vector<vector<int>> result_b = find_shortest_paths_without_each_edge(graph, n - 1);
  vector<vector<int>> rev_result_a = find_shortest_paths_without_each_edge(rev_graph, 0);
  vector<vector<int>> rev_result_b = find_shortest_paths_without_each_edge(rev_graph, n - 1);
  assert(1.0 * clock() / CLOCKS_PER_SEC <= 0.7);
  int ans = INT_MAX;
  if (result_a.back()[n - 1] != INT_MAX && result_b.back()[0] != INT_MAX) {
    ans = result_a.back()[n - 1] + result_b.back()[0];
  }
  for (int u = 0; u < n; u++) {
    for (auto [from, to, weight, cost, id] : graph[u]) {
      int AB = INT_MAX, BA = INT_MAX;
      AB = min(AB, Get(result_a, id, n - 1));
      if (Get(result_a, id, to) != INT_MAX && Get(rev_result_b, id, from) != INT_MAX) {
        AB = min(AB, Get(result_a, id, to) + Get(rev_result_b, id, from) + weight);
      }
      BA = min(BA, Get(result_b, id, 0));
      if (Get(result_b, id, to) != INT_MAX && Get(rev_result_a, id, from) != INT_MAX) {
        BA = min(BA, Get(result_b, id, to) + Get(rev_result_a, id, from) + weight); 
      }
      if (AB == INT_MAX || BA == INT_MAX) {
        continue;
      }
      ans = min(ans, AB + BA + cost);
    }
  }
  cout << (ans == INT_MAX ? -1 : ans) << "\n";
}
 
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  solve();
}

Compilation message (stderr)

ho_t4.cpp: In function 'std::vector<std::vector<int> > find_shortest_paths_without_each_edge(std::vector<std::vector<edge> >, int)':
ho_t4.cpp:79:12: warning: variable 'flag' set but not used [-Wunused-but-set-variable]
   79 |       bool flag = true;
      |            ^~~~

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