Given a linked list, swap every two adjacent nodes and return its head.
For example,
Given 1->2->3->4
, you should return the list as 2->1->4->3
.
Your algorithm should use only constant space. You may not modify the values in the list, only nodes itself can be changed.
题解:
code:
public ListNode swapPairs(ListNode head) {
ListNode p = new ListNode(0);
p.next = head;
ListNode tmp = p,curr = p;
while(curr.next!=null && curr.next.next!=null){
tmp = curr.next;
curr.next = tmp.next;
tmp.next = curr.next.next;
curr.next.next = tmp;
curr = tmp;
}
return p.next;
}