Given a linked list, swap every two adjacent nodes and return its head.
You may not modify the values in the list’s nodes, only nodes itself may be changed.
Example:
Given 1->2->3->4, you should return the list as 2->1->4->3.
Solution:
Simple implementation
/**
* 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(0);
ListNode* prev = dummy;
ListNode* cur = head;
ListNode* next;
dummy->next = head;
while(cur){
if(next = cur->next){
prev->next = next;
cur->next = next->next;
next->next = cur;
prev = cur;
cur = cur->next;
}
else{
break;
}
}
return dummy->next;
}
};