def breadthFirstSearch(problem, verbose=False): """ Perform a Breadth-First search on the given problem and return a solution. NOTE: This is a graph based implementation of the algorithm, please be aware of the memory overhead.""" start = Node(problem, state = problem.initialState()) solution = Solution(verbose) if problem.goalTest(start.state()): return solution.setGoalNode(start) frontier = Queue(items=[start]) explored = set() while True: solution.trackProgress(frontier, explored) if frontier.isEmpty(): raise NoSolutionFoundError() node = frontier.dequeue() explored.add(node.state()) for action in problem.applicableActions(node.state()): child = Node(problem, node, action) if child not in frontier and child.state() not in explored: if problem.goalTest(child.state()): return solution.setGoalNode(child) else: frontier.enqueue(child)
