Compute a moving average on a stream

Q: Compute a moving average on a stream

This question evaluates understanding of streaming data structures, sliding-window aggregation, and the time/space trade-offs involved in maintaining running statistics over recent inputs, testing algorithmic efficiency and numerical handling skills.

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Question

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Design a data structure to compute the moving average over the last N values from a stream.

Input/Operations

Initialize with an integer window size N .
Repeatedly receive values x (integers or floats).
After each new value arrives, return the average of the most recent min(N, count_so_far) values.

Constraints/Expectations

Each update should be O(1) time.
Use O(N) memory.

Example

If N = 3 and the stream is 1, 10, 3, 5:

after 1 → 1.0
after 10 → (1+10)/2 = 5.5
after 3 → (1+10+3)/3 = 4.666...
after 5 → (10+3+5)/3 = 6.0

Compute a moving average on a stream

Quick Overview

Input/Operations

Constraints/Expectations

Example

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