cp/codeforces/974/e.cc
2025-03-07 12:52:53 -05:00

124 lines
2.5 KiB
C++

#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;
}
// }}}