LeetCode Partition List

//  44ms
 1 /**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode *partition(ListNode *head, int x) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        ListNode a(0),b(0);
        ListNode* heada,*taila ,*headb,*tailb ;
        heada=taila=&a;
        headb=tailb=&b;
        ListNode *p,*r;
        p=head;
        while(p)
        {
            if(p->val<x)
            {
                taila->next=p;
                p=p->next;
                taila=taila->next;
            }
            else
            {
                tailb->next=p;
                p=p->next;
                tailb=tailb->next;
            }
        }
        tailb->next=NULL;
        taila->next=headb->next;
        return heada->next;
    }
};