#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
const double INF = 1e18;
double solve(int N, int M, int K, int H,
vector<int> x, vector<int> y,
vector<int> c, vector<int> arr){
K = min(K, 100); // batasi K agar tidak terlalu besar
vector<vector<pair<int,int>>> adj(N);
for(int i = 0; i < M; i++){
adj[x[i]].push_back({y[i], c[i]});
adj[y[i]].push_back({x[i], c[i]});
}
vector<vector<double>> dist(N, vector<double>(K+1, INF));
priority_queue<pair<double, pair<int,int>>,
vector<pair<double,pair<int,int>>>,
greater<>> pq;
dist[0][K] = 0.0;
pq.push({0.0, {0, K}});
while(!pq.empty()){
auto [d, state] = pq.top(); pq.pop();
int u = state.fi;
int k = state.se;
if(d > dist[u][k]) continue;
for(auto &[v, w] : adj[u]){
if(dist[v][k] > d + w){
dist[v][k] = d + w;
pq.push({dist[v][k], {v, k}});
}
if(arr[u] == 2 && k > 0){
double nd = d + w / 2.0;
if(dist[v][k-1] > nd){
dist[v][k-1] = nd;
pq.push({nd, {v, k-1}});
}
}
}
}
double ans = *min_element(dist[H].begin(), dist[H].end());
return (ans >= INF/2 ? -1.0 : ans);
}
