HR, then a phone call. It's strange how they rejected me. I got the solution pretty fast (~10 mins), but they asked me to test a function that deals with random numbers. Sure, my test cases were pretty crappy, but they were looking for a specific way of testing it which I didn't grasp.

I don't think their hiring bar is high; it's just really specific what they're looking for.

Write a function:

random_walk(

trans_probs, # a list of transition probabilities between each state in a directed graph (see example below)

start_state, # the state to start the walk from

num_steps, # the number of steps in the random walk to simulate

)

that returns a map from states to the number of times that state was visited.