Submission #1089085

#	Time	Username	Problem	Language	Result	Execution time	Memory
1089085		LucasLe	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	209 ms	68112 KiB

commuter_pass

#include <bits/stdc++.h>

#define                int  long long
#define              moony  long long
#define                pii  pair<int, int>
#define                 fi  first
#define                 se  second
#define                 ld  long double
#define                 vi  vector<int>
#define                vii  vector<vector<int>>
#define             all(v)  (v).begin(), (v).end()
#define       rep(i, a, b)  for (int i = (a), _b = (b); i <= _b; ++i)
#define       per(i, b, a)  for (int i = (b), _a = (a); i >= _a; --i)

using namespace std;

const int MOD = 1e9 + 7;

int add(int a, int b) {
  a += b;
  if (a >= MOD) a -= MOD;
  return a;
}

int mul(int a, int b) {
  (a *= b) %= MOD;
  return a;
}

int ceil(int x, int y) {
  return (x + y - 1) / y;
}

int bin_pow(int x, int y) {
  int res=1;
  while(y){if(y&1)res=res*x%MOD;x=x*x%MOD;y>>=1;}
  return res;
}

const int INF = 1e17;
const int maxn = 1e6 + 5;

int n, m, S, T, U, V, ans;
vector<int> trace[maxn + 5];
vector<pair<int, int>> g[maxn + 5];

vector<int> dijkstra(int s) {
  vector<int> dist(n + 1, -1);
  dist[s] = 0;
  priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> pq;
  pq.push({dist[s], s});
  while (!pq.empty()) {
    auto [d, u] = pq.top();
    pq.pop();
    if (d != dist[u]) continue;
    for (auto [v, cost] : g[u]) {
      if (dist[v] == -1 || d + cost < dist[v]) {
        dist[v] = d + cost;
        pq.push({dist[v], v});
      }
    }
  }
  return dist;
}

vector<int> trace_dijkstra(int s) {
  vector<int> dist(n + 1, -1);
  dist[s] = 0;
  priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> pq;
  pq.push({dist[s], s});
  while (!pq.empty()) {
    auto [d, u] = pq.top();
    pq.pop();
    if (d != dist[u]) continue;
    for (auto [v, cost] : g[u]) {
      if (dist[v] == -1 || d + cost < dist[v]) {
        dist[v] = d + cost;
        trace[v].clear();
        trace[v].push_back(u);
        pq.push({dist[v], v});
      } else if (dist[v] == d + cost) {
        trace[v].push_back(u);
      }
    }
  }
  return dist;
}

void solve(int tc) {
  cin >> n >> m;
  cin >> S >> T >> U >> V;
  for (int i = 0; i < m; ++i) {
    int u, v, c; cin >> u >> v >> c;
    g[u].push_back({v, c});
    g[v].push_back({u, c});
  }
  vector<int> du = dijkstra(U);
  vector<int> dv = dijkstra(V);
  trace_dijkstra(S);
  ans = du[V];
  vector<int> dist(n + 1, -1);
  dist[T] = dv[T];
  priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> pq;
  pq.push({dist[T], T});
  while (!pq.empty()) {
    auto [d, u] = pq.top();
    pq.pop();
    if (d != dist[u]) continue;
    ans = min(ans, du[u] + dist[u]);
    for (int v : trace[u]) {
      if (dist[v] == -1 || dist[v] > min(dist[u], dv[u])) {
        dist[v] = min(dist[u], dv[u]);
        pq.push({dist[v], v});
      }
    }
  }
  for (int i = 0; i <= n; ++i) dist[i] = -1;
  dist[T] = du[T];
  pq.push({dist[T], T});
  while (!pq.empty()) {
    auto [d, u] = pq.top();
    pq.pop();
    if (d != dist[u]) continue;
    ans = min(ans, dv[u] + dist[u]);
    for (int v : trace[u]) {
      if (dist[v] == -1 || dist[v] > min(dist[u], du[u])) {
        dist[v] = min(dist[u], du[u]);
        pq.push({dist[v], v});
      }
    }
  }
  cout << ans;
}

signed main() {

  ios_base::sync_with_stdio(false);
  cin.tie(0); cout.tie(0);

  int tc = 1;
  //cin >> tc;

  for (int i = 1; i <= tc; ++i) {
    solve(i);
  }
}

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