feat(cf): 894

codeforces/974/e.cc

@@ -0,0 +1,124 @@
+#include <bits/stdc++.h>  // {{{
+
+// https://codeforces.com/blog/entry/96344
+
+#pragma GCC optimize("O2,unroll-loops")
+#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
+
+using namespace std;
+
+template <typename T>
+[[nodiscard]] static T MIN() {
+  return std::numeric_limits<T>::min();
+}
+
+template <typename T>
+[[nodiscard]] static T MAX() {
+  return std::numeric_limits<T>::max();
+}
+
+template <typename T>
+[[nodiscard]] static T sc(auto&& x) {
+  return static_cast<T>(x);
+}
+
+template <typename T>
+[[nodiscard]] static T sz(auto&& x) {
+  return static_cast<T>(x.size());
+}
+
+#define prln(...) std::println(__VA_ARGS__)
+#define pr(...) std::print(__VA_ARGS__)
+
+#ifdef LOCAL
+#define dbgln(...) std::println(__VA_ARGS__)
+#define dbg(...) std::print(__VA_ARGS__)
+#endif
+
+using ll = long long;
+using ld = long double;
+template <typename T>
+using ve = std::vector<T>;
+template <typename T, size_t N>
+using ar = std::array<T, N>;
+template <typename T1, typename T2>
+using pa = std::pair<T1, T2>;
+
+#define ff first
+#define ss second
+#define eb emplace_back
+#define pb push_back
+#define all(x) (x).begin(), (x).end()
+#define rall(x) (x).rbegin(), (x).rend()
+//  }}}
+
+void solve() {
+  int n, m, h;
+  cin >> n >> m >> h;
+  unordered_set<int> horses;
+
+  int horse;
+  for (int i = 0; i < h; ++i) {
+    cin >> horse;
+    horses.insert(horse);
+  }
+
+  ve<ve<pa<int, ll>>> graph(n + 1);
+  for (int i = 0; i < m; ++i) {
+    int u, v;
+    ll w;
+    cin >> u >> v >> w;
+    graph[u].eb(v, w);
+    graph[v].eb(u, w);
+  }
+
+  ve<ll> marian(n + 1, MAX<ll>()), robin(n + 1, MAX<ll>());
+
+  auto djikstra = [&](int start, ve<ll>& delta) {
+    priority_queue<tuple<ll, int, bool>, ve<tuple<ll, int, bool>>, greater<>>
+        pq;
+    delta[start] = 0;
+    pq.emplace(delta[start], start, horses.contains(start));
+    unordered_set<int> seen;
+
+    while (!pq.empty()) {
+      auto [d0, u, took] = pq.top();
+      pq.pop();
+      if (d0 > delta[u] && !took) continue;
+      if (took) seen.insert(u);
+      for (auto [v, w] : graph[u]) {
+        ll d1 = d0 + (took ? w / 2 : w);
+        bool take = took || horses.contains(v);
+        if (d1 < delta[v]) {
+          delta[v] = d1;
+          pq.emplace(d1, v, take);
+        }
+      }
+    }
+  };
+
+  djikstra(1, marian);
+  djikstra(n, robin);
+
+  ll ans = MAX<ll>();
+  for (int node = 1; node <= n; ++node) {
+    ans = min(ans, max(marian[node], robin[node]));
+  }
+
+  prln("{}", ans == MAX<ll>() ? -1 : ans);
+}
+
+int main() {  // {{{
+  cin.tie(nullptr)->sync_with_stdio(false);
+  cin.exceptions(cin.failbit);
+
+  int t = 1;
+  cin >> t;
+
+  while (t--) {
+    solve();
+  }
+
+  return 0;
+}
+// }}}