CS188 searches by pyTony

def genericSearch(problem, fringe, h=nullHeuristic):
    """
    Generic Search in search tree

    Your search algorithm needs to return a list of actions that reaches
    the goal.  Make sure to implement a graph search algorithm © pyTony
    """
    start = problem.getStartState()
    closed = set()
    fringe.push(((0, 0, start), []))
    while not fringe.isEmpty():
        (costHere, _, state), directions = fringe.pop()
        if problem.isGoalState(state):
            return directions
        if state not in closed:
            closed.add(state)
            for node, direction, cost in problem.getSuccessors(state):
                fringe.push(((costHere + cost, h(node, problem), node),
                            directions + [direction]))


def depthFirstSearch(problem):
    """
    Search the deepest nodes in the search tree first
    """
    return genericSearch(problem, util.Stack())

def breadthFirstSearch(problem):
    """
    Search the shallowest nodes in the search tree first.
    """
    return genericSearch(problem, util.Queue())

def cost(((c, h, n), direction)):
    return c + h

def uniformCostSearch(problem):
    """
    Search the node of least total cost first.
    """
    return genericSearch(problem, util.PriorityQueueWithFunction(cost))

def aStarSearch(problem, heuristic=nullHeuristic):
    """
    Search the node that has the lowest combined cost and heuristic first.
    """
    return genericSearch(problem, util.PriorityQueueWithFunction(cost), heuristic)