Add type hints to max_heap.py (#1960)

* Max heap implementation

* Update max_heap.py

* Update max_heap.py

* Update max_heap.py

* __len__ method added

* Update max_heap.py

Co-authored-by: halilpython <65048618+halilpython@users.noreply.github.com>
Co-authored-by: Christian Clauss <cclauss@me.com>

data_structures/heap/max_heap.py

@@ -0,0 +1,87 @@
+class BinaryHeap:
+    """
+    A max-heap implementation in Python
+    >>> binary_heap = BinaryHeap()
+    >>> binary_heap.insert(6)
+    >>> binary_heap.insert(10)
+    >>> binary_heap.insert(15)
+    >>> binary_heap.insert(12)
+    >>> binary_heap.pop()
+    15
+    >>> binary_heap.pop()
+    12
+    >>> binary_heap.get_list
+    [10, 6]
+    >>> len(binary_heap)
+    2
+    """
+
+    def __init__(self):
+        self.__heap = [0]
+        self.__size = 0
+
+    def __swap_up(self, i: int) -> None:
+        """ Swap the element up """
+        temporary = self.__heap[i]
+        while i // 2 > 0:
+            if self.__heap[i] > self.__heap[i // 2]:
+                self.__heap[i] = self.__heap[i // 2]
+                self.__heap[i // 2] = temporary
+            i //= 2
+
+    def insert(self, value: int) -> None:
+        """ Insert new element """
+        self.__heap.append(value)
+        self.__size += 1
+        self.__swap_up(self.__size)
+
+    def __swap_down(self, i: int) -> None:
+        """ Swap the element down """
+        while self.__size >= 2 * i:
+            if 2 * i + 1 > self.__size:
+                bigger_child = 2 * i
+            else:
+                if self.__heap[2 * i] > self.__heap[2 * i + 1]:
+                    bigger_child = 2 * i
+                else:
+                    bigger_child = 2 * i + 1
+            temporary = self.__heap[i]
+            if self.__heap[i] < self.__heap[bigger_child]:
+                self.__heap[i] = self.__heap[bigger_child]
+                self.__heap[bigger_child] = temporary
+            i = bigger_child
+
+    def pop(self) -> int:
+        """ Pop the root element """
+        max_value = self.__heap[1]
+        self.__heap[1] = self.__heap[self.__size]
+        self.__size -= 1
+        self.__heap.pop()
+        self.__swap_down(1)
+        return max_value
+
+    @property
+    def get_list(self):
+        return self.__heap[1:]
+
+    def __len__(self):
+        """ Length of the array """
+        return self.__size
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()
+    # create an instance of BinaryHeap
+    binary_heap = BinaryHeap()
+    binary_heap.insert(6)
+    binary_heap.insert(10)
+    binary_heap.insert(15)
+    binary_heap.insert(12)
+    # pop root(max-values because it is max heap)
+    print(binary_heap.pop())  # 15
+    print(binary_heap.pop())  # 12
+    # get the list and size after operations
+    print(binary_heap.get_list)
+    print(len(binary_heap))