| The `select_next_node` function takes as input the current node, the destination_node, a set of unvisited nodes, and a distance matrix, and returns the next node to visit. | |
| ### Solution Function Signature | |
| ```python | |
| def select_next_node(current_node: int, destination_node: int, unvisited_nodes: set, distance_matrix: np.ndarray) -> int: | |
| """ | |
| Select the next node to visit in a Traveling Salesman Problem (TSP) constructive heuristic. | |
| Args: | |
| current_node (int): The node currently being visited | |
| destination_node (int): The final destination node in the TSP tour | |
| unvisited_nodes (set): Set of nodes that haven't been visited yet | |
| distance_matrix (np.ndarray): NxN matrix where distance_matrix[i][j] is the distance from node i to j | |
| Returns: | |
| int: The selected next node to visit | |
| """ | |
| ``` |