Submission #505933

#	Time	Username	Problem	Language	Result	Execution time	Memory
505933		cig32	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	456 ms	32580 KiB

commuter_pass

#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
using namespace std;
mt19937_64 rng((int)std::chrono::steady_clock::now().time_since_epoch().count());
const int MAXN = 3e5 + 10;
const int MOD = 1e9 + 7;
#define int long long

int rnd(int x, int y) { // random number generator
  int u= uniform_int_distribution<int>(x, y)(rng); return u;
}
int dist[4][MAXN];
bool cmp(int a, int b) {
  return dist[0][a] > dist[0][b];
}
void solve(int tc) {
  int N, M;
  cin >> N >> M;
  int r[4]; for(int i=0; i<4; i++)cin >> r[i];
  vector<pair<int, int> > adj[N+1];
  vector<int> ok[N+1];
  for(int i=0; i<M; i++) {
    int a, b, c; cin >> a >> b >> c;
    adj[a].push_back({b, c});
    adj[b].push_back({a, c});
  }
  for(int i=0; i<4; i++) {
    for(int j=1; j<=N; j++) dist[i][j] = 1e17;
  }
  for(int i=0; i<4; i++) dist[i][r[i]] = 0;
  for(int i=0; i<4; i++) {
    bool vis[N+1] = {};
    priority_queue<pair<int, int>,vector<pair<int, int> >, greater<pair<int,int> > > pq;
    for(int j=1; j<=N; j++) pq.push({dist[i][j], j});
    while(pq.size()) {
      pair<int, int> t= pq.top(); pq.pop();
      if(!vis[t.second]) {
        vis[t.second] = 1;
        for(pair<int, int> x: adj[t.second]) {
          if(!vis[x.first] && dist[i][t.second] != 1e17 && dist[i][x.first] > dist[i][t.second] + x.second) {
            dist[i][x.first] = dist[i][t.second] + x.second;
            pq.push({dist[i][x.first], x.first});
          }
        }
      }
    }
  }
  vector<int> rg[N+1];
  for(int i=1; i<=N; i++) {
    for(pair<int,int> x: adj[i]) {
      if(dist[0][i] + x.second == dist[0][x.first] && dist[0][x.first] + dist[1][x.first] == dist[0][r[1]]) {
        ok[i].push_back(x.first);
        rg[x.first].push_back(i);
      }
    }
  }
  int p[N+1]; for(int i=1; i<=N; i++) p[i] = i;
  sort(p+1, p+N+1, cmp);
  int dp[N+1];
  for(int i=1; i<=N; i++) dp[i] = 1e17;
  int ans = dist[2][r[3]];
  for(int i=1; i<=N; i++) {
    int tar = p[i];
    dp[tar] = dist[3][tar];
    for(int x: ok[tar]) {
      dp[tar] = min(dp[tar], dp[x]);
    }
    ans = min(ans, dp[tar] + dist[2][tar]);
  }
  reverse(p+1, p+N+1);
  for(int i=1; i<=N; i++) {
    int tar = p[i];
    dp[tar] = dist[3][tar];
    for(int x: rg[tar]) {
      dp[tar] = min(dp[tar], dp[x]);
    }
    ans = min(ans, dp[tar] + dist[2][tar]);
  }
  cout << ans << "\n";
}

int32_t main(){
  ios::sync_with_stdio(0); cin.tie(0);
  int t = 1; //cin >> t;
  for(int i=1; i<=t; i++) solve(i);
}

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