The given list is 142 543 123 65 453 879 572
As we know that insertion sort is based on the idea of inserting records into an existing sorted file. To insert a record, we must find the proper place for the record to be inserted and this requires searching the list.
An insertion sort will have the worst-case when the list is reversely sorted i.e. in a decreasing order. So for the above given list the insertion sort exhibits its worse case when the list is in following order
879 572 543 453 434 142 123 65
Again since it is the property of the insertion sort that it searches for the correct position in the list for an element, so this technique exhibits its best case computing when the list is already sorted in ascending order as given below.
65 123 142 434 453 543 572 879
