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.
这道题给出代码很容易看懂。
AC:
/**
* 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) {
int temp;
ListNode *p1=head;
while(head!=NULL && head->next!=NULL)
{
temp=head->val;
head->val=head->next->val;
head->next->val=temp;
head=head->next->next;
}
return p1;
}
};
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