题解 | #链表分割#

/*
struct ListNode {
    int val;
    struct ListNode *next;
    ListNode(int x) : val(x), next(NULL) {}
};*/
class Partition {
public:
    ListNode* partition(ListNode* pHead, int x) 
    {
        struct ListNode* lesshead,*lesstail,*greaterhead,*greatertail;
        lesshead = lesstail = (struct ListNode*)malloc(sizeof(struct ListNode));
        greaterhead = greatertail = (struct ListNode*)malloc(sizeof       (struct ListNode));
        ListNode* cur = pHead;
        while(cur)
        {
            if(cur->val < x)
            {
                lesstail->next = cur;
                lesstail = lesstail->next;
            }
            else
            {
                greatertail->next = cur;
                greatertail = greatertail->next; 
            }
            cur = cur->next;
        }
        lesstail->next = greaterhead->next;
        greatertail->next = NULL;
        pHead = lesshead->next;
        free(greaterhead);
        free(lesshead);
        return pHead;
    }
};