Schedule Network Retries with Backoff

A mobile app at Nimbus Mobile fetches data from several endpoints. Each request may time out multiple times before succeeding, and the app retries with exponential backoff.

Implement a function that computes when each request finally succeeds, assuming requests are processed independently and each retry waits longer than the previous one.

Formal Specification

Given:

• timeouts: an array where timeouts[i] is the number of consecutive timeouts before request i succeeds.
• base_delay: the delay after the first timeout.
• max_retries: the maximum number of retries allowed.

For each request:

1. The first attempt starts at time 0.
2. If it times out, retry after delays: base_delay, 2 * base_delay, 4 * base_delay, ...
3. If the request succeeds within max_retries, return the total elapsed wait time before success.
4. If it still has not succeeded after max_retries, return -1 for that request.

Return an array of results for all requests.