Shell Sort implementation in Python

Author: OmkarPathak

Programs/P53_ShellSort.py

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+# Author: OMKAR PATHAK
+# This program illustrates the shell sort implementation in Python
+
+# According to Wikipedia "Shell sort or Shell's method, is an in-place comparison sort.
+# It can be seen as either a generalization of sorting by exchange (bubble sort) or sorting by
+# insertion (insertion sort). The method starts by sorting pairs of elements far apart from each other,
+# then progressively reducing the gap between elements to be compared. Starting with far apart elements
+# can move some out-of-place elements into position faster than a simple nearest neighbor exchange."
+
+#  Best Case O(n logn); Average Case O(depends on gap sequence); Worst Case O(n)
+
+def shellSort(myList):
+    gap = len(myList) // 2
+    while gap > 0:
+        for i in range(gap, len(myList)):
+            currentItem = myList[i]
+            j = i
+            while j >= gap and myList[j - gap] > currentItem:
+                myList[j] = myList[j - gap]
+                j -= gap
+            myList[j] = currentItem
+        gap //= 2
+
+    return myList
+
+if __name__ == '__main__':
+    myList = [12, 23, 4, 5, 3, 2, 12, 81, 56, 95]
+    print(shellSort(myList))