housecricket

public static Boolean valueOf(boolean b) {
		return (b ? Boolean.TRUE : Boolean.FALSE);
	
}

housecricket

public class Person {

	private  String lastName; // required
	private  String firstName; // required
	private  String middleName; // required
	private  int bornYear; // required

	private  boolean isMale; // optional
	private  boolean isEmployed; // optional
	private  boolean isMarried; // optional

housecricket

# Initialize the dict with an empty list for each expert id:
friendships = {experts["id"]: [] for user in users}

# And loop over the friendship pairs to populate it:
for i, j in friendship_pairs:
    friendships[i].append(j)  # Add j as a friend of expert i
    friendships[j].append(i)  # Add i as a friend of expert j

housecricket

# Initialize the dict with an empty list for each expert id:
friendships = {expert["id"]: [] for expert in experts}

# And loop over the friendship pairs to populate it:
# {0: [1, 2], 1: [0, 2, 3], 2: [0, 1, 3], 3: [1, 2, 4], 4: [3, 5], 5: [4, 6, 7], 6: [5, 8], 7: [5, 8], 8: [6, 7, 9], 9: [8]}
for i, j in friendship_pairs:
    friendships[i].append(j)  # Add j as a friend of expert i
    friendships[j].append(i)  # Add i as a friend of expert j

housecricket

def number_of_friends(expert):
    expert_id = expert["id"]
    friend_ids = friendships[expert_id]
    return len(friend_ids)

housecricket

# 24
total_connections = sum(number_of_friends(expert) for expert in experts)
# length of the users list
num_experts = len(experts)           
# 24 / 10 == 2.4                
avg_connections = total_connections / num_experts

housecricket

# Create a list (user_id, number_of_friends).
num_friends_by_id = [(expert["id"], number_of_friends(expert))
                     for expert in experts]

# Sort the list
num_friends_by_id.sort(                                
       key=lambda id_and_friends: id_and_friends[1],   # by num_friends
       reverse=True)                                   # largest to smallest

# Each pair is (expert_id, num_friends):

housecricket

experts = [
    {"id": 0, "name": "Bill Gates"},
    {"id": 1, "name": "Mark Zuckerberg"},
    {"id": 2, "name": "Steve Jobs"},
    {"id": 3, "name": "Jeff Bezos"},
    {"id": 4, "name": "Ha Dong Nguyen"},
    {"id": 5, "name": "Trung Anh Dang"},
    {"id": 6, "name": "Sundar Pichai"},
    {"id": 7, "name": "Larry Page"},
    {"id": 8, "name": "Sergey Brin"},

housecricket

# foaf is short for "friend of a friend"
def foaf_ids_bad(expert):
    return [foaf_id
            for friend_id in friendships[expert["id"]]
            for foaf_id in friendships[friend_id]]

print(foaf_ids_bad(experts[1]))

housecricket

def friends_of_friends(expert):
    expert_id = expert["id"]
    return Counter(
        foaf_id
        # For each of my friends,
        for friend_id in friendships[expert_id]     
        # find their friends
        for foaf_id in friendships[friend_id]   
        # who aren't me  
        if foaf_id != expert_id