难度：Easy
解题思路：先在纸上画图。
dummy -> 1 -> 2 -> 3 -> 4
dummy 1 -> 2 -> 3 -> 4
| ^
|___________|
|---------|
| ^
dummy 1 2 -> 3 -> 4
| ^
|___________|
|---------|
| ^
dummy 1 <- 2 3 -> 4
| ^
|___________|
代码如下：
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/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
ListNode* swapPairs(ListNode* head) {
ListNode* dummy = new ListNode(-1), *cur = dummy;
dummy->next = head;
while(cur->next != NULL && cur->next->next != NULL)
{
ListNode *first = cur->next;
ListNode *second = first->next;
cur->next = second;
first->next = second->next;
second->next = first;
cur = first;
}
return dummy->next;
}
};
|
运行结果：3ms，超过11.49％
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