I am sharing my recent Coinbase interview experience for the Senior SDE (SDE3) position.

Online Assesment

1. 1 coding problem on code signal with 4 parts in 90 mins. Need to solve 3 parts to qualify.
   • Part 1: Create an in-memory data store with set, delete & update functions.
   • Part 2: Add scan keys and scan keys with prefix functions.
   • Part 3: Add set with ttl & update with ttl functions.
   • Part 4: Add undo and redo functions.
2. Behavioral questions + Logical assessment (20 mins each).

Virtual Onsite Rounds
Round 1

• 1 coding problem with multiple parts in 1 hour on codesignal. I solved 4 parts. Communication is also judged.
• Part 1: Design and code an interleaving iterator. Input: array1 = [1,2,3], array2 = [4,5,6] Output: [1,4,2,5,3,6]
• Part 2: Design and code a range based iterator: Input: start=1, end=10, step = 2 Output: [1,3,5,7,9]
• Part 3: Design and code an interleaving iterator which takes a list of array iterators.
• Part 4: Add a filter function in part 3.

Round 2

• Similiar to round 1. I solved 3 parts.
• Part 1: Given an list of lists with different length. Choose 1 element randomly from each list to prepare an array. Finally return N such arrays.
• Part 2: Make sure the result arrays are unqiue. Unique = all elements combined are not same.
• Part 3: Add a 'rarity' option for any element in any list in the input. Then that element should occur rarely in result arrays.