Coinbase QA Engineer Coding Questions

In the context of the rapidly changing environments of cryptocurrencies, validating API responses is essential. This requires implementing a utility that verifies response hierarchies and correctness in tests.
Problem statement: You need to create a function that performs a depth-first traversal on a response structure that is represented as a graph to validate if a given response satisfies a specific hierarchy. This function should return all valid nodes that meet the criteria within the API response hierarchy.
- Method Signature: def validate_api_response(node: Dict[str, Any], criteria: Callable[[Dict[str, Any]], bool]) -> List[Dict[str, Any]]
Example 1:
Input: {'node': {'valid': true, 'level': 1}, 'children': [{'valid': true, 'level': 2}]}, criteria = (node) => node['valid']
Output: [{'valid': true, 'level': 1}, {'valid': true, 'level': 2}]
Explanation: Both nodes are valid according to the criteria.
Example 2:
Input: {'node': {'valid': false}, 'children': [{'valid': false}, {'valid': true}]}, criteria = (node) => node['valid']
Output: [{'valid': true}]
Explanation: Only the last node meets the criteria.Constraints:
- 1 <= len(node) <= 1000
- Each node has structure {'valid': bool, 'level': int}

Coinbase handles thousands of transactions per second, so testing the transaction handling process efficiently is crucial. You need to develop a method to validate a stream of transactions for valid timestamps within a certain window.
Problem statement: Implement a function that verifies whether there are any duplicate timestamps in a stream of transactions that occur within a specified windowSize (in seconds). Your method should return true if a duplicate exists within that window, and false otherwise.
- Method Signature: def has_duplicate_transactions(transactions: List[Tuple[int, int]], window_size: int) -> bool
Example 1:
Input: [(1, 100), (2, 101), (3, 103), (4, 104), (5, 106)], window_size = 5
Output: False
Explanation: No duplicates within 5 seconds.
Example 2:
Input: [(1, 100), (2, 101), (3, 102), (4, 103), (5, 106), (6, 102)], window_size = 5
Output: True
Explanation: Duplicate timestamp 102 found within 5 seconds.Constraints:
- 1 <= len(transactions) <= 10000
- 0 <= transactions[i][0] <= 1000000
- 1 <= window_size <= 1000