Interview Questions

Sean L. - " import pandas as pd from datetime import datetime def findfastestlike(log: pd.DataFrame) -> pd.DataFrame: log=log.sortvalues(['userid','timestamp']) #get the prev event, time by user log['prevevent'] = log.groupby('userid')['event'].shift(1) log['prevtimestamp'] = log.groupby('userid')['timestamp'].shift(1) True only on rows where the previous event was a login and the current event is a like log['loginlike'] = (log['prevevent'] == 'log"See full answer

Alex W. - "Memory allocation happens for storing a reference pointer as well as the default size of the generic object class depending on the language this is called in. Assuming this is in a JVM, this data is stored in metaspace, and memory allocation happens in heap."See full answer

Lucas G. - "A confidence interval gives you a range of values where you can be reasonably sure the true value of something lies. It helps us understand the uncertainty around an estimate we've measured from a sample of data. Typically, confidence intervals are set at the 95% confidence level. For example, A/B test results show that variant B has a CTR of 10.5% and its confidence intervals are [9.8%, 11.2%], this means that based on our sampled data, we are 95% confident that the true avg CTR for variant B a"See full answer

Lucas G. - "Null hypothesis (H0): the coin is fair (unbiased), meaning the probability of flipping a head is 0.5 Alternative (H1): the coin is unfair (biased), meaning the probability of flipping a head is not 0.5 To test this hypothesis, I would calculate a p-value which is the probability of observing a result as extreme as, or more extreme than, what I say in my sample, assuming the null hypothesis is true. I could use the probability mass function of a binomial random variable to model the coin toss b"See full answer

Shar N. - "standard answer for this."See full answer

Himanshu G. - "First, I would start by defining what growth means in the context of this new feature whether it's user acquisition, engagement, retention, or revenue. Next, I’d identify clear KPIs that directly align with that growth goal. For example, if the feature aims to improve engagement, I’d track metrics like daily active users, session duration, or feature adoption rate. Once the KPIs are in place, I’d run an A/B test comparing user behavior with and without the feature. This would be followed by de"See full answer