Hudson River Trading Software Engineer Python interview questions

OA: - If 2 consecutive characters are the same, shrink the string until you can't anymore. Output final result. "ABBCDDC" -> "ABBCC" -> "ABB" -> "A" "AABBAA" -> "AAAA" -> "AA" -> "" - Construct an n-ary tree given a list of parents/values and k. Find max k-length path sum of the tree. Phone Screen: Describe a recent interesting bug that you have resolved. What's the purpose of 'yield' keyword? How does hashtable works? What happens in a lookup/insert operation when hashes of 2 different keys are the same? What's the time complexity of hashtable ops (lookup/delete/insert)? When does hashtable upsize/downsize? Runtime complexity? How does computer memory work? How does OS allocate memory to each process? Virtual mem vs physical mem? What happens when virtual mem exceeds physical mem? Stack vs heap. What stores in which? How does GIL work? What's the adv vs. disadv of GIL?