#include <iostream>
#include <deque>
#include <unordered_set>
using namespace std;
// Edge class that represents an edge in the graph
class Edge
{
public:
int to; // The index of the node that this edge leads to
int cost; // The cost of traveling along this edge
// Constructor to initialize the edge
Edge(int to, int cost) : to(to), cost(cost) {}
};
// Graph class that represents a graph with nodes and edges
class Graph
{
public:
vector<vector<Edge>> edges; // Adjacency list that stores the edges for each node
// Constructor to initialize the graph with n nodes
Graph(int n) : edges(n) {}
// Adds a new edge to the graph from node u to node v with the given cost
void addEdge(int u, int v, int cost)
{
edges[u].push_back(Edge(v, cost));
edges[v].push_back(Edge(u, cost));
}
};
// A utility function to find the shortest distances from the source node to all other nodes in the graph
// using breadth-first search
void bfs(const Graph& graph, int* distances, int source)
{
// Initialize distances to all nodes as infinite
int n = graph.edges.size();
for (int i = 0; i < n; i++)
distances[i] = -1;
// Create a deque to store the nodes that need to be processed
deque<int> q;
// Add the source node to the deque with distance 0
distances[source] = 0;
q.push_back(source);
// Process nodes in the deque until it is empty
while (!q.empty())
{
// Get the next node in the deque
int u = q.front();
q.pop_front();
// Iterate through
for (Edge edge : graph.edges[u])
{
// Calculate the new distance to the adjacent node
int v = edge.to;
int new_distance = distances[u] + edge.cost;
// If the new distance is smaller than the current distance, update the distance
if (distances[v] == -1 || new_distance < distances[v])
{
distances[v] = new_distance;
q.push_back(v);
}
}
}
}
int main()
{
int n;
// Read the number of cities
cin >> n;
// Read the type of each city
vector<int> city_types(n);
for (int& type : city_types)
cin >> type;
// Create a graph with n nodes
Graph graph(n);
// Read the roads and add them to the graph
for (int i = 0; i < n - 1; i++)
{
int u, v, cost;
cin >> u >> v >> cost;
graph.addEdge(u - 1, v - 1, cost);
}
// Find the indices of the sunflower fields and ports
unordered_set<int> sunflower_fields;
unordered_set<int> ports;
for (int i = 0; i < n; i++)
{
if (city_types[i] == 0)
ports.insert(i);
else if (city_types[i] == 1)
sunflower_fields.insert(i);
}
// Calculate the shortest distance from each sunflower field to a port
int total_distance = 0;
for (int field : sunflower_fields)
{
// Calculate the shortest distances from the current sunflower field to all nodes in the graph
int* distances = new int[n];
bfs(graph, distances, field);
// Find the port with the smallest distance to the sunflower field
int min_distance = -1;
for (int port : ports)
{
if (distances[port] != -1 && (min_distance == -1 || distances[port] < min_distance))
min_distance = distances[port];
}
// Add the distance to the total distance
total_distance += min_distance;
// Free the memory used by the array
delete[] distances;
}
// Print the total distance
cout << total_distance << endl;
return 0;
}