def is_goal_state(current_state, goal_state):
    return current_state == goal_state
def apply_action(current_state, action_effect):
    new_state = current_state.copy()
    new_state.update(action_effect)
    return new_state
def find_plan(initial_state, goal_state, actions):
    queue = [(initial_state, [])]
    visited_states = set()
    while queue:
        current_state, partial_plan = queue.pop(0)
        if is_goal_state(current_state, goal_state):
            return partial_plan
        if tuple(current_state.items()) in visited_states:
            continue
        visited_states.add(tuple(current_state.items()))
        for action in actions:
            if is_applicable(current_state, actions[action]['precondition']):
                next_state = apply_action(current_state, actions[action]['effect'])
                queue.append((next_state, partial_plan + [action]))
    print("No plan exists.")
    return None
def is_applicable(current_state, precondition):
    return all(current_state.get(key) == value for key, value in precondition.items())

initial_state = {'A': 'Table', 'B': 'Table'}
goal_state = {'A': 'B', 'B': 'Table'}
actions={'move_A_to_B':{'precondition':{'A':'Table','B':'Table'},'effect':{'A':'B'}},
    'move_B_to_Table':{'precondition':{'A':'Table','B':'B'},'effect':{'B':'Table'}}}
plan = find_plan(initial_state, goal_state, actions)
print(plan)

initial_state = {'A': 'Table', 'B': 'Table', 'C': 'Table'}
goal_state = {'A': 'B', 'B': 'C', 'C': 'Table'}
actions={'move_A_to_B':{'precondition':{'A':'Table','B':'Table'},'effect':{'A': 'B'}},
    'move_B_to_C':{'precondition':{'A':'B','B':'Table','C':'Table'},'effect':{'B':'C'}},
    'move_C_to_Table':{'precondition':{'A':'B','B':'C','C':'C'},'effect':{'C':'Table'}}}
plan = find_plan(initial_state, goal_state, actions)
print(plan)