Oliver's Blog
Search…
⌃K

Swap Nodes in Pairs

ID: 24; medium

Solution 1 (Java)

/**
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode() {}
* ListNode(int val) { this.val = val; }
* ListNode(int val, ListNode next) { this.val = val; this.next = next; }
* }
*/
class Solution {
public ListNode swapPairs(ListNode head) {
if (head == null || head.next == null) return head;
ListNode first = head;
ListNode second = head.next;
ListNode newHead = swapPairs(second.next);
first.next = newHead;
second.next = first;
return second;
}
}