- Use a
dummyHeadto bring some convenience.
- The terminating conditon is
no nodes leftor the total number of nodes is
oddso there is
one node left.
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.)
Input: head = [1,2,3,4]