Linked List· 25 min

Odd Even Linked List

LeetCode #328 · Medium · Interactive step-by-step visualization

Setup

Example inputhead = [1, 2, 3, 4, 5]
Step 1 / 10

Current step

1 / 10

Group by position, not by value. Odd and even refer to a node's place in the list, so the two groups interleave perfectly. Weave two chains in place, then join them.

Step log

head

head
1
2
3
4
5
null

list

1 → 2 → 3 → 4 → 5

Named pointer
Active node
Committed or completed
Detached or removed
odd-even-linked-list.java
1public ListNode oddEvenList(ListNode head) {
2    if (head == null || head.next == null) return head;
3    ListNode odd = head, even = head.next, evenHead = even;
4    while (even != null && even.next != null) {
5        odd.next = even.next;
6        odd = odd.next;
7        even.next = odd.next;
8        even = even.next;
9    }
10    odd.next = evenHead;
11    return head;
12}
● Java
Time
O(n)
Space
O(1)
Pattern
linked list
Frames
10
30 / 75