{"id":651,"date":"2025-07-15T13:11:00","date_gmt":"2025-07-15T07:41:00","guid":{"rendered":"https:\/\/codeanddebug.in\/blog\/?p=651"},"modified":"2025-07-15T13:11:01","modified_gmt":"2025-07-15T07:41:01","slug":"odd-even-linked-list-leetcode-328","status":"publish","type":"post","link":"https:\/\/codeanddebug.in\/blog\/odd-even-linked-list-leetcode-328\/","title":{"rendered":"Odd Even Linked List | Leetcode 328 | Brute to Optimal Solution"},"content":{"rendered":"\n

Given the head<\/code> of a singly linked list, group all the nodes with odd indices together followed by the nodes with even indices, and return the reordered list<\/em>.<\/p>\n\n\n\n

The first<\/strong> node is considered odd<\/strong>, and the second<\/strong> node is even<\/strong>, and so on.<\/p>\n\n\n\n

Note that the relative order inside both the even and odd groups should remain as it was in the input.<\/p>\n\n\n\n

You must solve the problem in O(1)<\/code> extra space complexity and O(n)<\/code> time complexity.<\/p>\n\n\n\n

Here’s the [Problem Link<\/span><\/mark><\/a><\/strong>] to begin with.<\/p>\n\n\n\n

Example 1:<\/strong><\/p>\n\n\n\n

\"\"\/<\/figure>\n\n\n\n
Input:<\/strong> head = [1,2,3,4,5]
Output:<\/strong> [1,3,5,2,4]<\/pre>\n\n\n\n
Example 2:<\/strong><\/p>\n\n\n\n
\"\"\/<\/figure>\n\n\n\n
Input:<\/strong> head = [2,1,3,5,6,4,7]
Output:<\/strong> [2,3,6,7,1,5,4]<\/pre>\n\n\n\n
Constraints:<\/strong><\/p>\n\n\n\n