Submission #1130794

#	Time	Username	Problem	Language	Result	Execution time	Memory
1130794		julia_08	Commuter Pass (JOI18_commuter_pass)	C++20	100 / 100	692 ms	75260 KiB

commuter_pass

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

using ll = long long;

const int MAXN = 4e5 + 10;
const ll INF = 1e18;

ll dist[MAXN][3];

int marc[MAXN][3];

int n, m;

vector<pair<int, int>> adj[MAXN];

void dijkstra(int v, int x){

  priority_queue<pair<ll, int>> q;

  for(int i=1; i<=4*n; i++) dist[i][x] = INF;

  dist[v][x] = 0; q.push({0, v});

  while(!q.empty()){

    auto [d, v] = q.top(); q.pop();

    if(marc[v][x]) continue;

    marc[v][x] = 1;

    for(auto [u, w] : adj[v]){
      if(dist[v][x] + w < dist[u][x]){
        dist[u][x] = dist[v][x] + w;
        q.push({-dist[u][x], u});
      }
    }

  }

}

int main(){
  cin.tie(0)->sync_with_stdio(0);

  cin >> n >> m;

  int s, t; cin >> s >> t;

  int u, v; cin >> u >> v;

  vector<pair<int, pair<int, int>>> edges;

  for(int i=1; i<=m; i++){
    int a, b, c; cin >> a >> b >> c;

    adj[a].push_back({b, c});
    adj[b].push_back({a, c});

    edges.push_back({a, {b, c}});
    edges.push_back({b, {a, c}});
  }

  dijkstra(s, 0);
  dijkstra(t, 1);

  for(auto e : edges){

    int x = e.first, y = e.second.first, w = e.second.second;

    adj[x + 3 * n].push_back({y + 3 * n, w});

    if(dist[x][0] + dist[x][1] == dist[t][0]){
      adj[x + n].push_back({y + 3 * n, w});
      adj[x + 2 * n].push_back({y + 3 * n, w});
    }

    if(dist[y][0] + dist[y][1] == dist[t][0]){
      adj[x].push_back({y + n, w});
      adj[x].push_back({y + 2 * n, w});
    }

    if(dist[x][0] + w + dist[y][1] == dist[t][0]) adj[x + n].push_back({y + n, 0});
    if(dist[x][1] + w + dist[y][0] == dist[s][1]) adj[x + 2 * n].push_back({y + 2 * n, 0});

  }

  if(dist[u][0] + dist[u][1] == dist[t][0]){
    adj[u].push_back({u + n, 0});
    adj[u].push_back({u + 2 * n, 0});
  }

  dijkstra(u, 2);

  cout << min({dist[v][2], dist[v + n][2], dist[v + 2 * n][2], dist[v + 3 * n][2]}) << "\n";

  return 0;
}

• Subtask 1: 16 / 16
• Subtask 2: 15 / 15
• Subtask 3: 24 / 24
• Subtask 4: 45 / 45