Python3 Program to Rotate the sub-list of a linked list from position M to N to the right by K places
Given a linked list and two positions ‘m’ and ‘n’. The task is to rotate the sublist from position m to n, to the right by k places. Examples:
Input: list = 1->2->3->4->5->6, m = 2, n = 5, k = 2 Output: 1->4->5->2->3->6 Rotate the sublist 2 3 4 5 towards right 2 times then the modified list are: 1 4 5 2 3 6 Input: list = 20->45->32->34->22->28, m = 3, n = 6, k = 3 Output: 20->45->34->22->28->32 Rotate the sublist 32 34 22 28 towards right 3 times then the modified list are: 20 45 34 22 28 32
Approach: For rotating the given sublist that extends from m to n element, move the list from (n-k+1)th to nth node to starting of sub-list to finish the rotation. If k is greater than size of sublist then we will take its modulo with size of sublist. So traverse through list using a pointer and a counter and we will save (m-1)th node and later make it point to (n-k+1)th node and hence bring (n-k+1)th node to the start(front) of sublist. Similarly we will save mth node and later make nth node point to it. And for keeping rest of list intact we will make (n-k)th node point to next node of n (maybe NULL). And finally we will get the k times right rotated sublist. Below is the implementation of the above approach:
Python3
import math
class Node:
def __init__( self , data):
self .data = data
self . next = None
def rotateSubList(A, m, n, k):
size = n - m + 1
if (k > size):
k = k % size
if (k = = 0 or k = = size):
head = A
while (head ! = None ):
print (head.data)
head = head. next
return
link = None
if (m = = 1 ) :
link = A
c = A
count = 0
end = None
pre = None
while (c ! = None ) :
count = count + 1
if (count = = m - 1 ) :
pre = c
link = c. next
if (count = = n - k) :
if (m = = 1 ) :
end = c
A = c. next
else :
end = c
pre. next = c. next
if (count = = n) :
d = c. next
c. next = link
end. next = d
head = A
while (head ! = None ) :
print (head.data, end = " " )
head = head. next
return
c = c. next
def push(head, val):
new_node = Node(val)
new_node.data = val
new_node. next = head
head = new_node
return head
if __name__ = = '__main__' :
head = None
head = push(head, 70 )
head = push(head, 60 )
head = push(head, 50 )
head = push(head, 40 )
head = push(head, 30 )
head = push(head, 20 )
head = push(head, 10 )
tmp = head
print ( "Given List: " , end = "")
while (tmp ! = None ) :
print (tmp.data, end = " " )
tmp = tmp. next
print ()
m = 3
n = 6
k = 2
print ( "After rotation of sublist: " , end = "")
rotateSubList(head, m, n, k)
|
Output:
Given List: 10 20 30 40 50 60 70
After rotation of sublist: 10 20 50 60 30 40 70
Time complexity: O(N) where N is the size of the given linked list
Auxiliary space: O(1) because it is using constant space
Please refer complete article on Rotate the sub-list of a linked list from position M to N to the right by K places for more details!
Last Updated :
31 Aug, 2022
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