Added shell sort

shell_sort.py

@@ -0,0 +1,49 @@
+
+
+# Python program for implementation of Shell Sort
+
+def shellSort(arr):
+
+	# Start with a big gap, then reduce the gap
+	n = len(arr)
+	gap = n // 2
+
+	# Do a gapped insertion sort for this gap size.
+	# The first gap elements a[0..gap-1] are already in gapped
+	# order. Keep adding one more element until the entire array
+	# is gap sorted
+	while gap > 0:
+
+		for i in range(gap,n):
+
+			# add a[i] to the elements that have been gap sorted
+			# save a[i] in temp and make a hole at position i
+			temp = arr[i]
+
+			# shift earlier gap-sorted elements up until the correct
+			# location for a[i] is found
+			j = i
+			while j >= gap and arr[j-gap] > temp:
+				arr[j] = arr[j-gap]
+				j -= gap
+
+			# put temp (the original a[i]) in its correct location
+			arr[j] = temp
+		gap = gap // 2
+
+
+# Driver code to test above
+arr = [ 12, 34, 54, 2, 3]
+
+n = len(arr)
+print ("Array before sorting:")
+for i in range(n):
+	print(arr[i],end=" "),
+
+shellSort(arr)
+
+print ("\nArray after sorting:")
+for i in range(n):
+	print(arr[i],end=" "),
+
+