numStops.py

def numStops(self, start, end, maxStops):
        """
        Wrapper function to calculate the number of stops
        Args:
            start    (str):    Starting city
            end      (str):    Destination city
            maxStops (int):    number of maximum stops allows

        Returns:
            int: calclated number of routes
        """
        return self.findRoutes(start, end, 0, maxStops)
    
    def findRoutes(self, start, end, depth, maxStops):
        """
        Recursive function to calculate the number of stops
        Args:
            start    (str):    Starting city
            end      (str):    Destination city
            maxStops (int):    number of maximum stops allows
            depth    (int):    current depth of recursion

        Returns:
            int: calclated number of routes
        """

        visited =[]
        routes = 0
        # Check if start and end nodes exists in route table
        if start in self.routesTable and end in self.routesTable:
            depth = depth + 1
            if depth > maxStops:  # Check if depth level is within limit
                return 0
            visited.append(start) # mark start as visited

            for adj in self.routesTable[start]:
                '''
                If destination matches, we increment route
				count, then continue to next node at same depth
				'''
                if adj == end:
                    routes = routes + 1
                
                '''
                If destination does not match, and
				destination node has not yet been visited,
				we recursively traverse destination node
				'''
                if adj not in visited and adj != end:
                    depth = depth - 1
                    routes += self.findRoutes(adj, end, depth, maxStops)
        else:
            return "No Such route"
        
        # unmark the start node before leaving recursive func
        if start in visited:
            visited.remove(start)
        return routes