My system design question was to design a heatmap. Pretty much user can input any range of times (in minutes) and I want to be able to see the density of drivers on the map color coded You don't have to worry about the actual color coding part (assume you have some UI that will take in the count input and do the coloring for you). I did well on the coding and was told I was rejected on the system design round. Was wondering if anyone can give a good solution to this?