Level 5Exercise #109

Running median

Return the median after each streamed number using two heaps.

What you’ll practice

This Level 5 exercise focuses on two heaps in the Algorithms curriculum. Solve the challenge prompt above using clear, idiomatic Python and the relevant language or standard-library tools.

Relevant Python reference: heapq — Heap queue algorithm.

Sample Test Cases

Example #1

Input:running_medians([2,1,5])

Output:[2.0,1.5,2.0]

Reference Solution

Reveal Reference Solution

def running_medians(values: list[int]) -> list[float]:
    import heapq
    low, high, result = [], [], []
    for value in values:
        heapq.heappush(low, -value)
        heapq.heappush(high, -heapq.heappop(low))
        if len(high) > len(low): heapq.heappush(low, -heapq.heappop(high))
        result.append(float(-low[0]) if len(low) > len(high) else (-low[0]+high[0])/2)
    return result

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Running median

What you’ll practice

Sample Test Cases

Further Reading

Reference Solution