JavaArithmetic/src/LeetCode/LeetCode24.java at master · wpq2014/JavaArithmetic · GitHub

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package LeetCode;

public class LeetCode24 {

// 24. Swap Nodes in Pairs

// https://leetcode.com/problems/swap-nodes-in-pairs/description/

// 时间复杂度: O(n)

// 空间复杂度: O(1)

public ListNode swapPairs(ListNode head) {

ListNode dummyHead = new ListNode(0);

dummyHead.next = head;

ListNode p = dummyHead;

while(p.next != null && p.next.next != null ){

ListNode node1 = p.next;

ListNode node2 = node1.next;

ListNode next = node2.next;

node2.next = node1;

node1.next = next;

p.next = node2;

p = node1;

}

return dummyHead.next;

}