Performance practice

Opening your lesson

The operations team has sent a new mixture of traces, quote requests and cache commands. You have already seen the underlying techniques. The names, values and boundaries have changed, so start from the contract rather than the shape of an earlier answer.

Choose what deserves a count and what deserves a key. A count of comparisons is not a latency measurement, and a hit rate doesn't prove that cached results are fresh. Work through each small function independently. Use the supplied examples to confirm output shape, then check empty collections, repeated requests and exact limits. You can choose any implementation that preserves the required behavior. No new library feature is introduced in this practice set.

import json

def process_payload(payload: str) -> str:
    data = json.loads(payload)
    n = data['size']
    k = min(data['take'], n)
    result = k * (2 * n - k - 1) // 2
    return json.dumps(result)

A removal from a list of length n shifts n minus one remaining elements. A front removal shifts every reference after index zero. List the first few remaining lengths. The closed-form count uses constant arithmetic rather than replaying the shifts.

Choose your character

Your Work Gym account