Heap Sort added

Author: neha030

Sorting Algorithms/heap_sort.py

@@ -0,0 +1,79 @@
+'''
+HEAP SORT
+It is a sorting technique based on the heap data structure.
+Heap is a complete binary tree, in which every level except the last, is filled
+completely with its nodes, and nodes are far left.
+We implement this sorting in an array using Max Heap, in which the parent node 
+value is greater than it child node values. 
+'''
+def heapify(arr, length, index):
+    # base case
+    # we will call this function until the largest number is the index...
+    largest_num_index = index
+    left_index = (index * 2) + 1
+    right_index = (index * 2) + 2
+ 
+    if(left_index < length and arr[index] < arr[left_index]):
+        largest_num_index = left_index
+ 
+    if(right_index < length and arr[largest_num_index] < arr[right_index]):
+        largest_num_index = right_index
+ 
+    # if index is not the largest, make it the largest!
+    # and run it again!
+    if(largest_num_index != index):
+        arr[index], arr[largest_num_index] = arr[largest_num_index], arr[index]
+        heapify(arr, length, largest_num_index)
+ 
+ 
+def heap_sort(arr):
+    # need array length to create indices
+    length = len(arr)
+ 
+    for index in range(length, -1, -1):
+        # ask about functions modifying arrays without return value
+        # build max heap
+        heapify(arr, length, index)
+ 
+    # for each sorted heap, swap the root and the last number
+    for index in range(length - 1, 0, -1):
+        arr[index], arr[0] = arr[0], arr[index]
+        # then call heapify again with the new array
+        heapify(arr, index, 0)
+ 
+ 
+# Taking Elements to be Sorted
+
+data = []
+n = int(input("Enter elements to be sorted :"))
+ 
+for i in range(n):
+    data.append(int(input()))
+    
+# Sending element to get sorted
+heap_sort(data)
+ 
+# Priting Elements after Getting Sorted
+for d in data:
+    print(d, end = " ")
+
+
+'''
+INPUT
+Enter elements to be sorted : 5
+30
+50
+10
+20
+40
+
+OUTPUT
+10 20 30 40 50
+
+Time Complexity:
+Best Case: O (nlogn)
+Average Case: O (nlogn)
+Worst Case: O (nlogn)
+Space Complexity: O (1)
+'''
+