Why Splitwise tests financial logic in LLD - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to calculate the total amount owed by a user.

LLD

total_owed = sum(expense.amount for expense in user.expenses if expense.paid_by != [1])

Drag options to blanks, or click blank then click option'

Auser.id

Bexpense.id

Cexpense.paid_by

Duser.name

Attempts:

3 left

💡 Hint

Common Mistakes

Using the expense ID instead of the payer's ID.

Comparing with user name instead of user ID.

The total amount owed by a user is the sum of expenses not paid by the user, identified by user.id.

2fill in blank

medium

Complete the code to split an expense evenly among participants.

LLD

share = expense.amount / [1]

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Asum(expense.participants)

Bexpense.amount

Cexpense.paid_by

Dlen(expense.participants)

Attempts:

3 left

💡 Hint

Common Mistakes

Dividing by the amount itself.

Using the payer instead of participants count.

The expense amount is divided evenly by the number of participants to find each person's share.

3fill in blank

hard

Fix the error in the code that calculates the balance for each user.

LLD

balance = user.paid_amount - sum(user.owed_amounts.get([1], 0) for user in users)

Drag options to blanks, or click blank then click option'

Auser.name

Buser.id

Cexpense.id

Duser.paid_amount

Attempts:

3 left

💡 Hint

Common Mistakes

Using user.name which may not be unique.

Using expense.id which is unrelated.

To get the owed amount for the specific user, use user.id as the key in owed_amounts dictionary.

4fill in blank

hard

Fill both blanks to create a dictionary of user balances where keys are user IDs and values are their net balances.

LLD

balances = {user.[1]: user.[2] for user in users}

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Aid

Bbalance

Cname

Dpaid_amount

Attempts:

3 left

💡 Hint

Common Mistakes

Using user names as keys which may not be unique.

Using paid_amount instead of balance for values.

The dictionary keys should be user IDs and values should be their net balances.

5fill in blank

hard

Fill all three blanks to filter expenses where the amount is greater than zero and the payer is not the current user.

LLD

filtered_expenses = [expense for expense in expenses if expense.[1] > [2] and expense.[3] != current_user.id]

Drag options to blanks, or click blank then click option'

Aamount

B0

Cpaid_by

Duser_id

Attempts:

3 left

💡 Hint

Common Mistakes

Using user_id instead of paid_by for payer.

Checking amount less than zero.

We filter expenses with amount greater than zero and exclude those paid by the current user.