#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
const long double INF = 1e30;
struct State {
int node;
int used;
long double dist;
bool operator<(const State& other) const {
return dist > other.dist; // for min-heap
}
};
double solve(int N, int M, int K, int H, vector<int> x, vector<int> y, vector<int> c, vector<int> arr) {
vector<vector<pair<int, long double>>> adj(N);
for (int i = 0; i < M; i++) {
adj[x[i]].emplace_back(y[i], (long double)c[i]);
adj[y[i]].emplace_back(x[i], (long double)c[i]);
}
vector<vector<long double>> dist(N, vector<long double>(K + 1, INF));
priority_queue<State> pq;
for (int start : arr) {
dist[start][0] = 0.0;
pq.push({start, 0, 0.0});
}
while (!pq.empty()) {
State cur = pq.top(); pq.pop();
int u = cur.node, used = cur.used;
long double d = cur.dist;
if (d > dist[u][used]) continue;
for (auto& [v, w] : adj[u]) {
if (used + 1 <= K && dist[v][used + 1] > d + w) {
dist[v][used + 1] = d + w;
pq.push({v, used + 1, dist[v][used + 1]});
}
}
}
long double ans = INF;
for (int i = 0; i <= K; i++) {
ans = min(ans, dist[H][i]);
}
return (ans >= INF ? -1.0 : (double)ans);
}
