// not my code, code by ai
#include <bits/stdc++.h>
using namespace std;
const double INF = 1e18;
const int mxN = 2e5+100;
const int mxK = 32;
double dp[mxN][mxK];
vector<pair<int, double>> adj[mxN];
struct State {
int node, usedK;
double cost;
bool operator>(const State &other) const { return cost > other.cost; }
};
double solve(int N, int M, int K, int H, vector<int> x, vector<int> y, vector<int> c, vector<int> arr) {
// Reset adjacency list and dp array
for (int i = 0; i < N; ++i) {
adj[i].clear();
for (int j = 0; j <= K; ++j) dp[i][j] = INF;
}
// Build adjacency list
for (int i = 0; i < M; ++i) {
adj[x[i]].emplace_back(y[i], c[i]);
adj[y[i]].emplace_back(x[i], c[i]);
}
priority_queue<State, vector<State>, greater<State>> pq;
dp[0][0] = 0.0;
pq.push({0, 0, 0.0});
while (!pq.empty()) {
auto [u, usedK, cost] = pq.top();
pq.pop();
if (cost > dp[u][usedK]) continue;
for (auto [v, w] : adj[u]) {
double new_cost = cost + w;
if (arr[v] == 0) new_cost = 0; // Reset time if special ability 0
if (dp[v][usedK] > new_cost) {
dp[v][usedK] = new_cost;
pq.push({v, usedK, new_cost});
}
if (arr[v] == 2 && usedK < K) {
double reduced_cost = new_cost / 2.0;
if (dp[v][usedK + 1] > reduced_cost) {
dp[v][usedK + 1] = reduced_cost;
pq.push({v, usedK + 1, reduced_cost});
}
}
}
}
double result = INF;
for (int i = 0; i <= K; ++i) result = min(result, dp[H][i]);
return (result == INF) ? -1 : result;
}
