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LeetCode/reverse-nodes-in-k-group
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Given a linked list, reverse the nodes of a linked list k at a time and return its modified list. | |
k is a positive integer and is less than or equal to the length of the linked list. If the number of nodes is not a multiple of k then left-out nodes in the end should remain as it is. | |
Example: | |
Given this linked list: 1->2->3->4->5 | |
For k = 2, you should return: 2->1->4->3->5 | |
For k = 3, you should return: 3->2->1->4->5 | |
Note: | |
Only constant extra memory is allowed. | |
You may not alter the values in the list's nodes, only nodes itself may be changed. | |
My code: | |
# Definition for singly-linked list. | |
# class ListNode: | |
# def __init__(self, x): | |
# self.val = x | |
# self.next = None | |
class Solution: | |
def reverseKGroup(self, head, k): | |
""" | |
:type head: ListNode | |
:type k: int | |
:rtype: ListNode | |
""" | |
if head==None: | |
return None | |
count=1 | |
result=[] | |
tmp_record=[] | |
while head.next!=None: | |
if count%k==0 and count!=0: | |
result.append(head.val) | |
for i in range(k-1): | |
result.append(tmp_record[k-i-2]) | |
tmp_record=[] | |
else: | |
tmp_record.append(head.val) | |
head=head.next | |
count+=1 | |
if count%k==0: | |
result.append(head.val) | |
for i in range(k-1): | |
result.append(tmp_record[k-i-2]) | |
else: | |
for i in range(len(tmp_record)): | |
result.append(tmp_record[i]) | |
result.append(head.val) | |
return result | |
Solution: | |
https://leetcode.com/problems/reverse-nodes-in-k-group/ |