# | Time | Username | Problem | Language | Result | Execution time | Memory |
---|---|---|---|---|---|---|---|
1253820 | anfi | Cyberland (APIO23_cyberland) | C++20 | 0 ms | 0 KiB |
#include <bits/stdc++.h>
using namespace std;
const int N = 10005;
const int K = 105;
const double INF = 1e18;
const double EPS = 1e-9;
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
int T;
cin >> T;
while (T--) {
int n, m, k;
cin >> n >> m >> k;
vector<int> type(n);
vector<vector<pair<int, int>>> graph(n);
for (int i = 0; i < n; i++) {
cin >> type[i];
}
for (int i = 0; i < m; i++) {
int u, v, w;
cin >> u >> v >> w;
graph[u].emplace_back(v, w);
graph[v].emplace_back(u, w);
}
double dist[N][K][2];
for (int i = 0; i < n; i++) {
for (int j = 0; j <= k; j++) {
dist[i][j][0] = dist[i][j][1] = INF;
}
}
priority_queue<tuple<double, int, int, int>, vector<tuple<double, int, int, int>>, greater<>> pq;
dist[0][k][0] = 0.0;
pq.emplace(0.0, 0, k, 0);
double ans = INF;
while (!pq.empty()) {
auto [d, u, r, used] = pq.top();
pq.pop();
if (d > dist[u][r][used] + EPS) continue;
if (u == n - 1) {
ans = min(ans, d);
}
if (used == 0 && type[u] == 1 && r > 0) {
if (d < dist[u][r-1][1] - EPS) {
dist[u][r-1][1] = d;
pq.emplace(d, u, r-1, 1);
}
}
for (auto [v, w] : graph[u]) {
double nd = d + (used == 0 ? (double)w : (double)w / 2.0);
if (nd < dist[v][r][0] - EPS) {
dist[v][r][0] = nd;
pq.emplace(nd, v, r, 0);
}
}
}
if (ans == INF) {
cout << "-1\n";
} else {
cout << fixed << setprecision(10) << ans << '\n';
}
}
return 0;
}