Prefix Cache Reuse Length

Problem

Compute how many leading tokens two prompts share, which is how much of the KV cache can be reused between them.

The signature is prefix_cache_reuse(prompt_a, prompt_b). Return the length of the longest common prefix.

Hint

Shared system prompts make most requests in a session share long prefixes.

case 1

in: [[1,2,3],[1,2,4]]

expected: 2

case 2

in: [[1,2],[3,4]]

expected: 0

case 3

in: [[],[1]]

expected: 0

case 4

in: [[5,5,5],[5,5,5]]

expected: 3

Starter codePython

def prefix_cache_reuse(prompt_a, prompt_b):
    # Your code here
    pass

4 test cases · run your code against them in the editor