Update bubble_sort.py

Author: ammalik221

Searching_and_Sorting/bubble_sort.py

@@ -1,4 +1,88 @@
 """
-Bubble Sort implementation in python 3.0
+Bubble Sort Algorithm implementation in python 3.0
+
+I have implemented three functions in this file, each implementing bubble sort but each with
+some extra technique which can drastically affect runtime, as the size of array increases.
+
+To compare the running time of each, I have used a variable num_of_comparisions.
 """
 
+def bubble_sort(arr):
+    """ Naive approach of bubble sort """
+    num_of_comparisions = 0
+    for i in range(len(arr)-1):
+        # number of comparisions in each iteration is len(array) - 1 
+        for j in range(len(arr)-1):
+            num_of_comparisions += 1
+            # compare the two elements
+            # if the first element is greater than the one after it, swap them
+            # after the all the comparisions, the biggest element ends up at the last position of the array
+            if arr[j] > arr[j+1]:
+                temp = arr[j+1]
+                arr[j+1] = arr[j]
+                arr[j] = temp
+    print(num_of_comparisions)
+    return arr
+  
+
+def bubble_sort_intermediate(arr):
+    """ The difference here is that, I am stopping the iterations once the array is sorted. """
+    num_of_comparisions = 0
+    for i in range(len(arr)-1):
+        count = 0
+        for j in range(len(arr)-1):
+            num_of_comparisions += 1
+            if arr[j] > arr[j+1]:
+                temp = arr[j+1]
+                arr[j+1] = arr[j]
+                arr[j] = temp
+                count += 1
+        # Checks, if the array is sorted
+        if count == 0:
+            break
+    print(num_of_comparisions)
+    return arr
+  
+
+def bubble_sort_advanced(arr):
+    """ The difference here is at each iteration, I am reducing the length variable,
+        which stops the extra number of steps that the code was taking by comparing the elements
+        that were already sorted. """
+    num_of_comparisions = 0
+    length = len(arr) - 1
+    for i in range(len(arr)-1):
+        count = 0
+        for j in range(length):
+            num_of_comparisions += 1
+            if arr[j] > arr[j+1]:
+                temp = arr[j+1]
+                arr[j+1] = arr[j]
+                arr[j] = temp
+                count += 1
+        length -= 1
+        if count == 0:
+            break
+    print(num_of_comparisions)
+    return arr
+  
+  
+if __name__ == "__main__":
+    # test case
+    a = [1,24,35,45,34,4,89,77,7,87,76,7,56,53,44,6,4,43,54,54,6,8,78,23,4,7,78,77,4,42,34,23,23]
+    
+    # output - 
+    # num_of_comparisions = 1024
+    # [1, 4, 4, 4, 4, 6, 6, 7, 7, 7, 8, 23, 23, 23, 24, 34, 34, 35, 42, 43, 44, 45, 53, 54, 54, 56, 76, 77, 77, 78, 78, 87, 89]
+    print(bubble_sort(a))
+    
+    # output - 
+    # num_of_comparisions = 800
+    # [1, 4, 4, 4, 4, 6, 6, 7, 7, 7, 8, 23, 23, 23, 24, 34, 34, 35, 42, 43, 44, 45, 53, 54, 54, 56, 76, 77, 77, 78, 78, 87, 89]
+    a = [1,24,35,45,34,4,89,77,7,87,76,7,56,53,44,6,4,43,54,54,6,8,78,23,4,7,78,77,4,42,34,23,23]
+    print(bubble_sort_intermediate(a))
+    
+    # output - 
+    # num_of_comparisions = 500
+    # [1, 4, 4, 4, 4, 6, 6, 7, 7, 7, 8, 23, 23, 23, 24, 34, 34, 35, 42, 43, 44, 45, 53, 54, 54, 56, 76, 77, 77, 78, 78, 87, 89]
+    a = [1,24,35,45,34,4,89,77,7,87,76,7,56,53,44,6,4,43,54,54,6,8,78,23,4,7,78,77,4,42,34,23,23]
+    print(bubble_sort_advanced(a))