Payment handling in LLD - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define the main class for payment processing.

LLD

class [1]:
    def __init__(self):
        self.transactions = []

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ATransactionManager

BPaymentProcessor

COrderHandler

DUserAccount

Attempts:

3 left

💡 Hint

Common Mistakes

Using unrelated class names like OrderHandler or UserAccount.

The main class handling payments is typically called PaymentProcessor.

2fill in blank

medium

Complete the code to add a method that initiates a payment.

LLD

def [1](self, amount, method):
    # code to start payment
    pass

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Ainitiate_payment

Bprocess_order

Ccancel_payment

Drefund_payment

Attempts:

3 left

💡 Hint

Common Mistakes

Using method names like cancel_payment or refund_payment which do not start payments.

The method to start a payment is called initiate_payment.

3fill in blank

hard

Fix the error in the method that validates payment status.

LLD

def validate_status(self, status):
    if status == [1]:
        return True
    return False

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A"completed"

Bcompleted

CTrue

D"pending"

Attempts:

3 left

💡 Hint

Common Mistakes

Not using quotes around string literals.

The status should be compared as a string literal, so it must be in quotes: "completed".

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps transaction IDs to amounts for successful payments.

LLD

successful_payments = {txn['id']: txn[1] for txn in transactions if txn['status'] [2] 'success'}

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A['amount']

B==

C!=

D['status']

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong dictionary keys or incorrect comparison operators.

The dictionary maps transaction IDs to their amounts, so use ['amount']. The filter checks for status equal to 'success', so use ==.

5fill in blank

hard

Fill all three blanks to create a method that refunds payments over a certain amount and updates their status.

LLD

def refund_large_payments(self, threshold):
    for txn in self.transactions:
        if txn['amount'] [1] threshold:
            self.process_refund(txn[2])
            txn['status'] = [3]

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A>

B['id']

C'refunded'

D<=

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong comparison operators or wrong keys for refund.

The method refunds payments where amount is greater than threshold (>), calls refund with transaction ID (['id']), and sets status to 'refunded'.