Merge pull request #210 from Abhi8756/feature/heap-sort-python

Add Heap Sort implementation in Python

Author: Pradeepsingh61

Python/algorithms/sorting/heap_sort_Abhijit.py

@@ -0,0 +1,105 @@
+"""
+Algorithm: Heap Sort
+Description: Comparison-based sorting algorithm using binary heap data structure
+Time Complexity: O(n log n) for all cases
+Space Complexity: O(1) auxiliary space
+Author: Abhijit
+"""
+
+def heapify(arr, n, i):
+    """
+    Heapify a subtree rooted with node i.
+    
+    Args:
+        arr: Array to heapify
+        n: Size of heap
+        i: Root index of subtree to heapify
+    """
+    largest = i
+    left = 2 * i + 1
+    right = 2 * i + 2
+
+    if left < n and arr[left] > arr[largest]:
+        largest = left
+
+    if right < n and arr[right] > arr[largest]:
+        largest = right
+
+    if largest != i:
+        arr[i], arr[largest] = arr[largest], arr[i]
+        heapify(arr, n, largest)
+
+
+def heap_sort(input_data):
+    """
+    Sorts an array using heap sort algorithm.
+
+    Args:
+        input_data: List of comparable elements to sort
+
+    Returns:
+        List: Sorted array in ascending order
+
+    Raises:
+        ValueError: When input is invalid
+        TypeError: When input is not a list
+    """
+    if input_data is None:
+        raise ValueError("Input cannot be None")
+    
+    if not isinstance(input_data, list):
+        raise TypeError("Input must be a list")
+    
+    if not input_data:
+        return []
+    
+    # Create a copy to avoid modifying original
+    arr = input_data.copy()
+    n = len(arr)
+
+    # Build max heap
+    for i in range(n // 2 - 1, -1, -1):
+        heapify(arr, n, i)
+
+    # Extract elements from heap one by one
+    for i in range(n - 1, 0, -1):
+        arr[0], arr[i] = arr[i], arr[0]
+        heapify(arr, i, 0)
+
+    return arr
+
+
+def main():
+    """Test the algorithm with example cases."""
+    # Test Case 1
+    test_data = [64, 34, 25, 12, 22, 11, 90]
+    result = heap_sort(test_data)
+    print(f"Original: {test_data}")
+    print(f"Sorted: {result}")
+
+    # Test Case 2 - Edge case
+    edge_case = []
+    try:
+        result = heap_sort(edge_case)
+        print(f"Empty array result: {result}")
+    except ValueError as e:
+        print(f"Handled edge case: {e}")
+
+    # Test Case 3 - Single element
+    single_element = [42]
+    result = heap_sort(single_element)
+    print(f"Single element: {single_element} -> {result}")
+
+    # Test Case 4 - Already sorted
+    sorted_array = [1, 2, 3, 4, 5]
+    result = heap_sort(sorted_array)
+    print(f"Already sorted: {sorted_array} -> {result}")
+
+    # Test Case 5 - Reverse sorted
+    reverse_sorted = [5, 4, 3, 2, 1]
+    result = heap_sort(reverse_sorted)
+    print(f"Reverse sorted: {reverse_sorted} -> {result}")
+
+
+if __name__ == "__main__":
+    main()