AdventOfCode/2017/24/test.py

def build_graph(node_list):
    """
    Build a graph where:
    - Each graph starts with a node containing `0`.
    - Nodes are connected if they share a common value, except `0` cannot connect to another `0`.
    """
    graph = {}
    
    # Parse nodes
    parsed_nodes = [tuple(map(int, node.split('/'))) for node in node_list]
    
    # Build adjacency list
    for node1 in parsed_nodes:
        for node2 in parsed_nodes:
            # Skip if both nodes contain `0`
            if node1 == node2 or (0 in node1 and 0 in node2):
                continue
            
            # Add edge if they share a common value
            if node1[0] == node2[0] or node1[1] == node2[1] or node1[0] == node2[1] or node1[1] == node2[0]:
                graph.setdefault(node1, []).append(node2)
                graph.setdefault(node2, []).append(node1)
    
    return graph

def find_paths(graph, start, visited=None, path=None):
    """
    Recursively find all paths starting from a given node.
    Ensures that each node is visited only once per path.
    """
    if visited is None:
        visited = set()
    if path is None:
        path = []

    visited.add(start)
    path.append(start)

    # Print the current path
    #print(" \--".join(f"{node[0]}/{node[1]}" for node in path))
    
    # Explore neighbors
    for neighbor in graph.get(start, []):
        if neighbor not in visited:
            find_paths(graph, neighbor, visited.copy(), path.copy())
    return path

def main():
    # Input list of nodes
    nodes = [
        "0/2", "2/2", "2/3", "3/4", "3/5", "0/1", "10/1", "9/10"
    ]

    # Build the graph
    graph = build_graph(nodes)
    results = []
    # Find and print all paths for each subgraph starting with a `0` node
    zero_nodes = [node for node in graph if 0 in node]
    for start in zero_nodes:
        print(f"Starting from {start[0]}/{start[1]}:")
        tmp = find_paths(graph, start)
        results.append(tmp)
    
    print(results)

if __name__ == "__main__":
    main()