[Leetcode] Partition List

/** * 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* pLess = NULL;        ListNode** ppLess = &pLess;                ListNode* pGreater = NULL;        ListNode** ppGreater = &pGreater;                ListNode* cur = head;                while (cur)        {            if (cur->val < x)            {                *ppLess = cur;                ppLess = &(cur->next);                            }            else            {                *ppGreater = cur;                ppGreater = &(cur->next);            }            cur = cur->next;        }                *ppLess = NULL;        *ppGreater = NULL;                if (pLess)        {            *ppLess = pGreater;            return pLess;        }        else            return pGreater;        return pLess;    }};