86. 分隔链表

/**
 * 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) {
        ListNode *mirror, *mirror1, *small, *large;
        mirror = new ListNode(0);
        mirror1 = new ListNode(-1);
        small = mirror;
        large = mirror1;
        while(head)
        {
            if(head->val<x)
            {
                small->next = head;
                small = small->next;
                head = head->next;
            }
            else
            {
                large->next = head;
                large = large->next;
                head = head->next;
            }
        }
        large->next = NULL;
        small->next = mirror1->next;
        return mirror->next;
      
    }
};