Large Codebase Bug Fix + New Methods | Dataford Interview Questions

Given a large codebase, find and fix a bug causing a failing test, then implement 2 new methods (explain approach before coding).

Asked in the karat_screen stage. For this exercise, the repository exposes a WordIndex class. Repair its count bookkeeping and implement insert(word) and count_prefix(prefix). The grader calls run_operations(operations) and expects outputs for query operations.

Contract

Each operation is ["insert"|"remove"|"count"|"prefix", value]. Return results for count and prefix operations in order.

Constraints

1 <= len(operations) <= 10^4
Each word and prefix contains lowercase English letters
1 <= len(word) <= 100
Removing an absent word has no effect
Duplicate words are allowed

Function Signature

def run_operations(operations):

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