Added doctest to heap.py (#11059)

data_structures/heap/heap.py

@@ -81,6 +81,9 @@ class Heap(Generic[T]):
     def max_heapify(self, index: int) -> None:
         """
         correct a single violation of the heap property in a subtree's root.
+
+        It is the function that is responsible for restoring the property
+        of Max heap i.e the maximum element is always at top.
         """
         if index < self.heap_size:
             violation: int = index
@@ -99,7 +102,29 @@ class Heap(Generic[T]):
                 self.max_heapify(violation)
 
     def build_max_heap(self, collection: Iterable[T]) -> None:
-        """build max heap from an unsorted array"""
+        """
+        build max heap from an unsorted array
+
+        >>> h = Heap()
+        >>> h.build_max_heap([20,40,50,20,10])
+        >>> h
+        [50, 40, 20, 20, 10]
+
+        >>> h = Heap()
+        >>> h.build_max_heap([1,2,3,4,5,6,7,8,9,0])
+        >>> h
+        [9, 8, 7, 4, 5, 6, 3, 2, 1, 0]
+
+        >>> h = Heap()
+        >>> h.build_max_heap([514,5,61,57,8,99,105])
+        >>> h
+        [514, 57, 105, 5, 8, 99, 61]
+
+        >>> h = Heap()
+        >>> h.build_max_heap([514,5,61.6,57,8,9.9,105])
+        >>> h
+        [514, 57, 105, 5, 8, 9.9, 61.6]
+        """
         self.h = list(collection)
         self.heap_size = len(self.h)
         if self.heap_size > 1:
@@ -108,7 +133,24 @@ class Heap(Generic[T]):
                 self.max_heapify(i)
 
     def extract_max(self) -> T:
-        """get and remove max from heap"""
+        """
+        get and remove max from heap
+
+        >>> h = Heap()
+        >>> h.build_max_heap([20,40,50,20,10])
+        >>> h.extract_max()
+        50
+
+        >>> h = Heap()
+        >>> h.build_max_heap([514,5,61,57,8,99,105])
+        >>> h.extract_max()
+        514
+
+        >>> h = Heap()
+        >>> h.build_max_heap([1,2,3,4,5,6,7,8,9,0])
+        >>> h.extract_max()
+        9
+        """
         if self.heap_size >= 2:
             me = self.h[0]
             self.h[0] = self.h.pop(-1)
@@ -122,7 +164,34 @@ class Heap(Generic[T]):
             raise Exception("Empty heap")
 
     def insert(self, value: T) -> None:
-        """insert a new value into the max heap"""
+        """
+        insert a new value into the max heap
+
+        >>> h = Heap()
+        >>> h.insert(10)
+        >>> h
+        [10]
+
+        >>> h = Heap()
+        >>> h.insert(10)
+        >>> h.insert(10)
+        >>> h
+        [10, 10]
+
+        >>> h = Heap()
+        >>> h.insert(10)
+        >>> h.insert(10.1)
+        >>> h
+        [10.1, 10]
+
+        >>> h = Heap()
+        >>> h.insert(0.1)
+        >>> h.insert(0)
+        >>> h.insert(9)
+        >>> h.insert(5)
+        >>> h
+        [9, 5, 0.1, 0]
+        """
         self.h.append(value)
         idx = (self.heap_size - 1) // 2
         self.heap_size += 1