Find Median from Data Stream - Codey

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Solution

Updated: 2026-02-23

Idea

Maintain two heaps: lower half (max-heap) and upper half (min-heap).

Approach

Push into max-heap, then move its top into min-heap.
Rebalance so max-heap has equal or one more element than min-heap.
Median is either top of max-heap (odd count) or average of both tops.

Why it works

Heaps keep halves ordered: all small <= large, and sizes differ by at most 1.

Code

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Complexity

Time: O(log n) per add, O(1) median

Space: O(n)

Solution

Updated: 2026-02-23

Idea

Maintain two heaps: lower half (max-heap) and upper half (min-heap).

Approach

Push into max-heap, then move its top into min-heap.
Rebalance so max-heap has equal or one more element than min-heap.
Median is either top of max-heap (odd count) or average of both tops.

Why it works

Heaps keep halves ordered: all small <= large, and sizes differ by at most 1.

Code

Loading...

Complexity

Time: O(log n) per add, O(1) median

Space: O(n)