#include "cyberland.h"
#include <bits/stdc++.h>
#define mk make_pair
#define pb push_back
#define vi vector <int>
#define vd vector <double>
#define paii pair<int, int>
using namespace std;
using tp = tuple<double, int, int>;
const double eps = 1e-9;
const double inf = 1e14;
double solve(int n, int m, int k, int h, vi x, vi y, vi c, vi a) {
vector<vd> d(n, vd(k + 1, inf));
vector<vector<paii>> g(n);
for (int i = 0; i < m; i++) {
g[x[i]].pb(mk(y[i], c[i]));
g[y[i]].pb(mk(x[i], c[i]));
}
d[0][0] = 0;
priority_queue<tp, vector<tp>, greater<tp>> pq;
pq.push({0, 0, 0});
while (!pq.empty()) {
auto [exp, who, used] = pq.top();
pq.pop();
if (d[who][used] - exp < -eps) {
continue;
}
if (who == h) {
continue;
}
for (auto [to, w] : g[who]) {
if (a[to] == 1) {
if (d[to][used] > exp + w) {
d[to][used] = exp + w;
pq.push({d[to][used], to, used});
}
} else if (a[to] == w) {
if (used < k - 1 && d[to][used + 1] > ((exp + (double) w) / 2)) {
d[to][used + 1] = (exp + (double) w) / 2;
pq.push({d[to][used + 1], to, used + 1});
}
if (d[to][used] > exp + w) {
d[to][used] = exp + w;
pq.push({d[to][used], to, used});
}
} else {
if (d[to][used] > 0) {
d[to][used] = 0;
pq.push({0, to, used});
}
}
}
}
double cur = d[h][0];
for (int i = 0; i <= k; i++) {
if (cur > d[h][i]) {
cur = d[h][i];
}
}
return cur;
}
