Function 5
Get Top K Customers by Spending
Min-Heap size k → O(n log k) · Cache on-demand · Customer Spending Service
Parameters
Complexity
Build Min-HeapO(n log k)
Extract k itemsO(k log k)
Cache hitO(1)
Min-Heap State (size k=3)
Heap kosong — run query dulu
Min-heap[0] = customer dengan spending terendah di top-K. Jika customer baru > min, replace dan reheapify.