Shell Sort added

Author: robinsingh-ai

Data Structures/Sorting Algorithms/ShellSort.py

@@ -0,0 +1,35 @@
+#Author : Robin Singh
+#Shell sort is an algorithm that first sorts the elements far apart from each other and successively reduces
+#the interval between the elements to be sorted. It is a generalized version of insertion sort
+#In shell sort, elements at a specific interval are sorted. The interval between the elements is gradually decreased
+#based on the sequence used. The performance of the shell sort depends on the type of sequence used for a given input array
+#We can use different sequences methods
+#Shell's original sequence: N/2 , N/4 , …, 1
+#Knuth's increments: 1, 4, 13, …, (3k – 1) / 2
+#Sedgewick's increments: 1, 8, 23, 77, 281, 1073, 4193, 16577...4j+1+ 3·2j+ 1
+
+#Complexity : Best Case = Average Case = O(nLogn)
+# Worst Case = O(n*n)
+
+
+
+
+
+def shellsort(a,n):
+
+    g = n // 2
+    while g > 0:
+        for i in range(g, n):
+            t = a[i]
+            j = i
+            while j >= g and a[j - g] > t:
+                a[j] = a[j - g]
+                j -= g
+
+            a[j] = t
+        g =g// 2
+
+if __name__ == '__main__':
+    a = [8,76,65,5,8,95,3,2,1,0]
+    shellsort(a,len(a))
+    print(a)