def IDS2(self):
        frontier = PriotyQueue(self.n)        
        limit = 0

        while True:
            depth = 0
            explored = []
            frontier.add(((self.source, ), depth))

            while frontier.empty() == False:
                pop_pair = frontier.pop()
                path = pop_pair[0]
                depth = pop_pair[1]
                node = path[-1]
                explored.append(node)

                if node == self.des:
                    print(explored)
                    self.returnPath = path[::-1]
                    self.expanded = explored
                    return
                
                for i in range(len(self.matrix)):
                    if (self.matrix[node][i] != 0 and i != path[len(path)-2]): 
                        level = depth - 1   
                        if (abs(level) <= limit):               
                            newPath = path + (i, )
                            frontier.add((newPath, level))

            limit += 1
            frontier.frontier.clear()
            print(explored)