Added language specific interview prep sections

docs/interview/ds/heap.md

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+# Heap
+
+A heap is a specialized tree-based data structure that satisfies the heap property: in a max-heap, for any given node I, the value of I is greater than or equal to the values of its children, while a min-heap has the value of I less than or equal to its children. Heaps are commonly implemented as arrays.
+
+Common applications include:
+- Priority queues
+- Heap sort algorithm
+- Finding kth largest/smallest elements
+- Implementing efficient graph algorithms (Dijkstra's)
+
+## Time Complexities
+
+- Insert element: O(log n)
+- Delete element: O(log n)
+- Get min/max element: O(1)
+- Build heap from array: O(n)
+- Heapify (fix heap property): O(log n)
+- Search for element: O(n)