Submission #330167

#	Time	Username	Problem	Language	Result	Execution time	Memory
330167		casperwang	Commuter Pass (JOI18_commuter_pass)	C++14	100 / 100	476 ms	25320 KiB

commuter_pass

#include <bits/stdc++.h>
#define int long long
#define pii pair<int,int>
#define ff first
#define ss second
#define pb push_back
using namespace std;

const int MAXN = 100000;
const int INF = 1e18;
int n, m;
int s, t, u, v;
int a, b, c;
vector <pii> path[MAXN+1];
int dpU[MAXN+1];
int dpV[MAXN+1];
pii arr[MAXN+1];
int ans = INF;
priority_queue <pii, vector<pii>, greater<pii>> nxt;

class Dijkstra{
  private:
    priority_queue <pii, vector<pii>, greater<pii>> nxt;
  public:
    int dis[MAXN+1];
    void init() {
      for (int i = 1; i <= n; i++)
        dis[i] = INF;
    }
    void shortest_path(int s) {
      init();
      dis[s] = 0;
      nxt.push(pii(0, s));
      while (nxt.size()) {
        int now = nxt.top().ss, d = nxt.top().ff;
        nxt.pop();
        for (pii e : path[now]) {
          if (d + e.ss < dis[e.ff]) {
            dis[e.ff] = d + e.ss;
            nxt.push(pii(dis[e.ff], e.ff));
          }
        }
      }
    }
} S, T, U, V;

void solve(int s) {
  for (int i = 1; i <= n; i++)
    arr[i] = pii(S.dis[i], i);
  sort(arr+1, arr+1+n);
  for (int i = 1; i <= n; i++) {
    int now = arr[i].ss, d = arr[i].ff;
    for (pii e : path[now]) {
      if (d + e.ss == S.dis[e.ff] && S.dis[now] + e.ss + T.dis[e.ff] == T.dis[s]) {
        dpU[e.ff] = min(dpU[e.ff], dpU[now]);
        dpV[e.ff] = min(dpV[e.ff], dpV[now]);
      }
    }
  }
  for (int i = 1; i <= n; i++) {
    ans = min(ans, dpU[i] + V.dis[i]);
    ans = min(ans, dpV[i] + U.dis[i]);
  }
}

signed main() {
  ios_base::sync_with_stdio(0), cin.tie(0);
  cin >> n >> m;
  cin >> s >> t;
  cin >> u >> v;
  for (int i = 0; i < m; i++) {
    cin >> a >> b >> c;
    path[a].pb(pii(b, c));
    path[b].pb(pii(a, c));
  }
  U.shortest_path(u);
  V.shortest_path(v);
  for (int i = 1; i <= n; i++) dpU[i] = U.dis[i];
  for (int i = 1; i <= n; i++) dpV[i] = V.dis[i];
  S.shortest_path(s);
  T.shortest_path(t);
  solve(s);
  cout << ans << "\n";
}

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