Interview Questions

Anonymous - "Functional requirements: (a) location tracking (b) check-in at nearby place (c) view historical checkins with how much time user stayed there (d) Mark checkout when out of proximity (e) analytics - checkins by user at given loc, top n places Out of scope: (a) checkin sharing with followers Non functional: (a) low latency (b) high availability (c) eventual consistency Scale: (a) QPS: 10M DAU * 2 checkins /86400 seconds (b) Yearly Data Volume: 10M* 0.1 KB *365 days HLD: user -> location servic"See full answer

Rg - "Used prefix & postfix sums, resetting the product when 0 was found"See full answer

Mark S. - "Range captures the difference between the highest and lowest value in a data set, while standard deviation measures the variation of elements from the mean. Range is extremely sensitive to outliers, it tells us almost nothing about the distribution of the data, and does not extrapolate to new data (a new value outside the range would invalidate the calculation). Standard deviation, on the other hand, offers us an insight into how closely data is distributed towards the mean, and gives us some pr"See full answer

Mark S. - "E(VAR(X))= VAR(X) VAR(X)= E[(X-E(X))^2] = E[X^2]-E[X]^2"See full answer

Emiliano I. - "Look for the main variables and see if there differences in the distributions of the buckets. Run a linear regression where the dependent variable is a binary variable for each bucket excluding one and the dependent variable is the main kpi you want to measure, if one of those coefficients is significant, you made a mistake. "See full answer

Sonveer K. - "na"See full answer