24. Swap Nodes in Pairs
Medium
30 Points
Linked List
Recursion
Given a linked list, swap every two adjacent nodes and return its head. You must solve the problem without modifying the values in the list's nodes (i.e., only nodes themselves may be changed.)
Examples
Example 1
Input: head = [1,2,3,4]
Output: [2,1,4,3]
Explanation:
Example 2
Input: head = []
Output: []
Example 3
Input: head = [1]
Output: [1]
Example 4
Input: head = [1,2,3]
Output: [2,1,3]
Constraints
The number of nodes in the list is in the range [0, 100].0 <= Node.val <= 100
24. Swap Nodes in Pairs
Medium
30 Points
Linked List
Recursion
Given a linked list, swap every two adjacent nodes and return its head. You must solve the problem without modifying the values in the list's nodes (i.e., only nodes themselves may be changed.)
Examples
Example 1
Input: head = [1,2,3,4]
Output: [2,1,4,3]
Explanation:
Example 2
Input: head = []
Output: []
Example 3
Input: head = [1]
Output: [1]
Example 4
Input: head = [1,2,3]
Output: [2,1,3]
Constraints
The number of nodes in the list is in the range [0, 100].0 <= Node.val <= 100