Given a linked list, swap every two adjacent nodes and return its head.
Example
Given 1->2->3->4, you should return the list as 2->1->4->3.
Challenge
Your algorithm should use only constant space. You may not modify the values in the list, only nodes itself can be changed.
Solution:
This is an easay question.
If there are more than two nodes behind, exchange the order of the following two nodes,
and then move the http://www.lintcode.com/en/problem/swap-nodes-in-pairs/pointer 2 places.
Leetcode link
Lintcode link
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> File Name: SwapNodesinPairs.java
> Author: Yao Zhang
> Mail: [email protected]
> Created Time: Wed 18 Nov 23:21:09 2015
************************************************************************/
public class {
public ListNode swapPairs(ListNode head) {
ListNode dummy = new ListNode(-1);
dummy.next = head;
head = dummy;
while (head.next != null && head.next.next != null){
ListNode temp = head.next;
head.next = temp.next;
temp.next = head.next.next;
head.next.next = temp;
head = head.next.next;
}
return dummy.next;
}
}
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