add insertion sort

Author: mcleber

README.md

@@ -15,7 +15,7 @@ This is my study repository.
 * recursion.
 * bubble sort.
 * selection sort.
-
+* insertion sort.
 
 ## Link
 

src/insertion_sort.py

@@ -0,0 +1,43 @@
+#!/usr/bin/env python3
+
+##
+# Insertion Sort
+##
+
+
+import numpy as np
+
+def insertion_sort(array):
+    """
+    Sorts an array using the insertion sort algorithm.
+    
+    The insertion sort algorithm builds the final sorted array one item at a time.
+    It repeatedly picks the next element and inserts it into its correct position 
+    among the already sorted elements.
+
+    Parameters:
+    array (numpy.ndarray): The array to be sorted.
+
+    Returns:
+    numpy.ndarray: The sorted array.
+    """
+    n = len(array)  # Get the length of the array
+
+    # Loop through each element starting from the second one
+    for i in range(1, n):
+        marked = array[i]  # Store the element to be inserted
+
+        j = i - 1  # Start comparing with the previous element
+        # Shift elements to the right to make space for the marked element
+        while j >= 0 and marked < array[j]:
+            array[j + 1] = array[j]  # Shift the element to the right
+            j -= 1  # Move to the previous element
+
+        # Insert the marked element at its correct position
+        array[j + 1] = marked
+
+    return array  # Return the sorted array
+
+# Example usage of the insertion_sort function
+sorted_array = insertion_sort(np.array([15, 34, 8, 3]))
+print("Sorted array:", sorted_array)  # Output: [ 3  8 15 34]