Heap and priority queue in Python

Built-in heapq

import heapq

heap = [5, 3, 9]
heapq.heapify(heap)
heapq.heappush(heap, 1)
print(heap[0])

Problems to practice

• Kth largest element
• Top K frequent elements
• Merge K sorted lists
• Median in stream

Interview guidance

heapq gives us a min-heap by default. For max-heap, push negatives.