https://github.com/emahtab/odd-even-linked-list
Odd Even Linked List
https://github.com/emahtab/odd-even-linked-list
leetcode linked-list odd-even problem-solving
Last synced: 5 months ago
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Odd Even Linked List
- Host: GitHub
- URL: https://github.com/emahtab/odd-even-linked-list
- Owner: eMahtab
- Created: 2020-02-13T19:07:16.000Z (over 6 years ago)
- Default Branch: master
- Last Pushed: 2020-04-10T11:34:14.000Z (about 6 years ago)
- Last Synced: 2025-06-06T01:05:15.852Z (about 1 year ago)
- Topics: leetcode, linked-list, odd-even, problem-solving
- Size: 2.93 KB
- Stars: 1
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# Odd Even Linked List
## https://leetcode.com/problems/odd-even-linked-list
Given a singly linked list, group all odd nodes together followed by the even nodes. Please note here we are talking about the node number and not the value in the nodes.
You should try to do it in place. The program should run in O(1) space complexity and O(nodes) time complexity.
```
Example 1:
Input: 1->2->3->4->5->NULL
Output: 1->3->5->2->4->NULL
Example 2:
Input: 2->1->3->5->6->4->7->NULL
Output: 2->3->6->7->1->5->4->NULL
```
**Note:**
1. The relative order inside both the even and odd groups should remain as it was in the input.
2. The first node is considered odd, the second node even and so on ...
# Implementation :
```java
/**
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode(int x) { val = x; }
* }
*/
class Solution {
public ListNode oddEvenList(ListNode head) {
if(head == null)
return head;
ListNode odd = head;
ListNode even = head.next;
ListNode evenHead = even;
while(even != null && even.next != null){
odd = odd.next = even.next;
even = even.next = odd.next;
}
odd.next = evenHead;
return head;
}
}
```
# References :
https://www.youtube.com/watch?v=bFR0ZvDt-J8