Python – Sort from Kth index in List
Given a list of elements, perform sort from Kth index of List.
Input : test_list = [7, 3, 7, 6, 4, 9], K = 2
Output : [7, 3, 4, 6, 7, 9]
Explanation : List is unsorted till 3 (1st index), From 2nd Index, its sorted.
Input : test_list = [5, 4, 3, 2, 1], K= 3
Output : [5, 4, 3, 1, 2]
Explanation : Only last two elements, 1, 2 are sorted.
Method #1 : Using loop + list slicing
This is one of the ways in which this task can be performed. In this, we extract each element before K in list and then perform list slice using slice symbol and perform sort over the extracted sliced list.
Python3
# Python3 code to demonstrate working of# Perform sort from Kth index# Using loop + list slicing# initializing listtest_list = [8, 4, 7, 3, 2, 14, 6]# printing original listprint("The original list : " + str(test_list))# initializing KK = 3# Using loop + list slicingres = []# Using loop to extract elements till Kfor idx, ele in enumerate(test_list): if idx < K: res.append(ele)# join sorted and unsorted segmentsres = res + sorted(test_list[K:])# printing resultprint("Partially sorted list : " + str(res)) |
The original list : [8, 4, 7, 3, 2, 14, 6] Partially sorted list : [8, 4, 7, 2, 3, 6, 14]
Time Complexity: O(n*logn), as sorted function is used.
Auxiliary Space: O(n), where n is the size of list
Method #2 : Using double List slicing
This is yet another way in which we perform this task. In this, we perform the task of list slicing for slicing the unsort part as well and perform concatenation, delivering a one liner alternative to solve this problem.
Python3
# Python3 code to demonstrate working of# Perform sort from Kth index# Using double List slicing# initializing listtest_list = [8, 4, 7, 3, 2, 14, 6]# printing original listprint("The original list : " + str(test_list))# initializing KK = 3# Using loop + list slicingres = []# Using loop to extract elements till K# Concatenating unsort and sorted part as one linerres = test_list[:K] + sorted(test_list[K:])# printing resultprint("Partially sorted list : " + str(res)) |
The original list : [8, 4, 7, 3, 2, 14, 6] Partially sorted list : [8, 4, 7, 2, 3, 6, 14]
Time Complexity: O(n*logn), as sorted function is used.
Auxiliary Space: O(n) where n is the number of elements in the list “test_list”.
