LeetCode Partition List

//  44ms
 1 /**
 2  * Definition for singly-linked list.
 3  * struct ListNode {
 4  *     int val;
 5  *     ListNode *next;
 6  *     ListNode(int x) : val(x), next(NULL) {}
 7  * };
 8  */
 9 class Solution {
10 public:
11     ListNode *partition(ListNode *head, int x) {
12         // Start typing your C/C++ solution below
13         // DO NOT write int main() function
14         ListNode a(0),b(0);
15         ListNode* heada,*taila ,*headb,*tailb ;
16         heada=taila=&a;
17         headb=tailb=&b;
18         ListNode *p,*r;
19         p=head;
20         while(p)
21         {
22             if(p->val<x)
23             {
24                 taila->next=p;
25                 p=p->next;
26                 taila=taila->next;
27             }
28             else
29             {
30                 tailb->next=p;
31                 p=p->next;
32                 tailb=tailb->next;
33             }
34         }
35         tailb->next=NULL;
36         taila->next=headb->next;
37         return heada->next;
38     }
39 };