Bank Automation: Simulate ATM Transactions with Balance and Overdraft Rules
Interview Experience
Round 1 Coding / OA
Problem
Simulate a bank account system. Implement deposit, withdraw, and transfer. Withdrawals fail if the account balance would fall below zero. Transfers atomically move funds between two accounts — if the source lacks funds, the transfer fails entirely.
python
class BankAccount:
def __init__(self, account_id: str, balance: float):
...
def deposit(self, amount: float) -> float:
**returns** new balance
...
def withdraw(self, amount: float) -> float: # raises InsufficientFundsError if fails
...
class Bank:
def __init__(self):
...
def add_account(self, account: BankAccount) -> None:
...
def transfer(self, from_id: str, to_id: str, amount: float) -> bool:
...
def get_balance(self, account_id: str) -> float:
...
Example
bank = Bank()
bank.add_account(BankAccount("ACC1", 500))
bank.add_account(BankAccount("ACC2", 100))
bank.transfer("ACC1", "ACC2", 200) -> True
bank.get_balance("ACC1") -> 300
bank.get_balance("ACC2") -> 300
bank.transfer("ACC2", "ACC1", 500) -> False # insufficient
Follow-ups
- How do you prevent race conditions if two threads transfer from the same account simultaneously?
- How would you implement a transaction history log with timestamps?
- What happens if
from_idorto_iddoesn't exist in the bank? - How would you add an overdraft limit so accounts can go negative up to a set threshold?
Full Details
Round 1 Coding / OA
Problem
Simulate a bank account system. Implement deposit, withdraw, and transfer. Withdrawals fail if the account balance would fall below zero. Transfers atomically move funds between two accounts — if the source lacks funds, the transfer fails entirely.
python
class BankAccount:
def __init__(self, account_id: str, balance: float):
...
def deposit(self, amount: float) -> float:
**returns** new balance
...
def withdraw(self, amount: float) -> float: # raises InsufficientFundsError if fails
...
class Bank:
def __init__(self):
...
def add_account(self, account: BankAccount) -> None:
...
def transfer(self, from_id: str, to_id: str, amount: float) -> bool:
...
def get_balance(self, account_id: str) -> float:
...
Example
bank = Bank()
bank.add_account(BankAccount("ACC1", 500))
bank.add_account(BankAccount("ACC2", 100))
bank.transfer("ACC1", "ACC2", 200) -> True
bank.get_balance("ACC1") -> 300
bank.get_balance("ACC2") -> 300
bank.transfer("ACC2", "ACC1", 500) -> False # insufficient
Follow-ups
- How do you prevent race conditions if two threads transfer from the same account simultaneously?
- How would you implement a transaction history log with timestamps?
- What happens if
from_idorto_iddoesn't exist in the bank? - How would you add an overdraft limit so accounts can go negative up to a set threshold?
Topics
About Ramp Interview Reports
This question was reported by a candidate who interviewed at Ramp. LeakCode aggregates interview reports from 10+ sources, including 1Point3Acres, Glassdoor, LeetCode Discuss, Blind, Reddit, Indeed, and Nowcoder. Each report is translated where necessary, deduplicated against existing entries, and tagged by company, role, round type, and reporting date.
Use this question as one calibration data point, not a memorization target. Companies typically rotate their question pools every 2-4 months; the exact wording of a 2024 question may differ from what you encounter today. The underlying pattern, difficulty level, and follow-up depth at Ramp are the higher-signal extractions to take from this report.
For broader preparation context, the Ramp interview process typically includes a recruiter screen, one or two technical phone screens, and a 4-5 round on-site loop covering coding, system design (at L4+ levels), and behavioral. Reports tagged on LeakCode show the round-by-round distribution and typical difficulty calibration. To browse questions filtered by round type and seniority, use the company hub linked above.
How To Practice This Type of Question
Solve similar problems on LeetCode under timed conditions (25-35 minutes per medium difficulty). The goal is pattern recognition: recognize the underlying technique (sliding window, two-pointer, BFS, memoized recursion, etc.) within 60-90 seconds of reading. Strong candidates verbalize their hypothesis out loud before coding, then iterate based on feedback. Weak candidates dive into implementation immediately, lose time on the wrong approach, and run out of time for follow-ups.
Companies update their question pools every 2-4 months. The exact wording of any given question may have been retired by the time you interview. Focus your prep on the pattern, not the specific problem. The patterns that appear in Ramp reports consistently are the ones worth investing in; one-off niche problems are not.
During Your Ramp Round
Apply the standard interview round template: clarify requirements (2-3 minutes), state your approach out loud and confirm direction with the interviewer (3-5 minutes), code with narration (15-25 minutes), test with concrete examples including edge cases (5 minutes), discuss optimization or trade-offs if time permits (5 minutes). This template is universally accepted across FAANG and adjacent companies; deviating from it produces weaker interviewer feedback signal.
The single most predictive failure mode in Ramp reports tagged "no hire": not asking clarifying questions. Interviewers are explicitly trained to weight this. Strong candidates ask 3-5 clarifying questions even on problems that look obvious; weak candidates dive into code immediately. The clarifying-question check is often the first signal recorded in the interviewer's written notes.