I usually don't write the type of code to find users within two degrees, so I thought it'd be a fun exercise in my fun-time language, Python. And did you mean

I usually don't write the type of code to find users within two degrees, so I thought it'd be a fun exercise in my fun-time language, Python. And did you mean users instead of friends? If a user is already a friend with someone, that means they can only be one degree away. Here's what I came up with. Is this about right? # Set up a mock DB holding users and relationships. # 1 is 1 degree from 2, 5 and 6 # 1 is 2 degrees from 3, 4, 6 # 1 is 3 degrees from 7 and 8 # 1 is 4 degrees from 7 and 8 people_store = [''] #0 -- put blank in 0 so we can have a one-based list. people_store.append([2,5,6]) #1 people_store.append([1,3]) #2 people_store.append([2,4,6]) #3 people_store.append([3,6,7,8]) #4 people_store.append([1]) #5 people_store.append([1,3,4]) #6 people_store.append([4,8]) #7 people_store.append([4,7,9]) #8 people_store.append([8]) #9 def find_users_within_x_degrees(user_id, degrees): """Given a user ID, find other users within two degrees.""" # Users that are within the degree range. # Start by adding current user's friends (1 degree). users_within_range = set(people_store[user_id]) # Keep track of user IDs that have been checked. checked_ids = set() # Start at 2, because we have already handled 1 degree above. for degree in range(2, degrees+1): # Get other users IDs and get their friends. Only do so for users we haven't checked. for other_user_id in users_within_range.difference(checked_ids): checked_ids.add(other_user_id) # Add other user's friends. users_within_range.update(people_store[other_user_id]) # Because friendships are reciprocal, if the number of degrees is > 1, the requested user_id will be in the set, and should be removed. if degrees > 1: users_within_range.remove(user_id) return users_within_range