Transaction history in LLD - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize the transaction list.

LLD

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

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

ANone

B{}

C[]

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using a dictionary {} instead of a list.

Initializing with None or 0.

We use an empty list [] to store transactions in order.

2fill in blank

medium

Complete the code to add a transaction to the history.

LLD

def add_transaction(self, transaction):
    self.transactions.[1](transaction)

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Ainsert

Bappend

Cremove

Dpop

Attempts:

3 left

💡 Hint

Common Mistakes

Using remove or pop which delete items.

Using insert without specifying index.

We use append to add a new transaction at the end of the list.

3fill in blank

hard

Fix the error in the method to get the last transaction.

LLD

def get_last_transaction(self):
    if not self.transactions:
        return None
    return self.transactions[[1]]

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A-1

B0

C1

Dlen(self.transactions)

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 returns the first transaction.

Using len(self.transactions) causes index error.

Index -1 accesses the last item in a list in Python.

4fill in blank

hard

Fill both blanks to filter transactions by minimum amount.

LLD

def filter_transactions(self, min_amount):
    return [t for t in self.transactions if t.[1] >= [2]]

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Aamount

Bmin_amount

Cdate

Dstatus

Attempts:

3 left

💡 Hint

Common Mistakes

Comparing wrong attributes like date or status.

Using wrong variable names.

We compare each transaction's amount to the min_amount parameter.

5fill in blank

hard

Fill all three blanks to create a dictionary of transaction IDs to amounts for completed transactions.

LLD

def get_completed_transactions(self):
    return {t.[1]: t.[2] for t in self.transactions if t.[3] == 'completed'}

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

Atransaction_id

Bamount

Cstatus

Ddate

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong keys or values in the dictionary.

Filtering by wrong attributes.

We map each transaction's transaction_id to its amount only if its status is 'completed'.