题解 | #链表分割#

/*
struct ListNode {
    int val;
    struct ListNode *next;
    ListNode(int x) : val(x), next(NULL) {}
};*/
//哨兵节点方法的好处在于可以统一进行尾插操作
class Partition 
{
public:
    ListNode* partition(ListNode* pHead, int x) 
    {
        ListNode * temphead = pHead;
        auto watcher1 = new ListNode(0);
        auto watcher2 = new ListNode(0);
        ListNode * temwat1 = watcher1;
        ListNode * temwat2 = watcher2;
        while(temphead)
        {
            if(temphead->val<x)
            {
                temwat1->next = temphead;
                temwat1=temwat1->next;
                temphead=temphead->next;
            }
            else 
            {
                temwat2->next = temphead;
                temwat2 = temwat2->next;
                temphead = temphead->next;
            }
        }
        temwat1->next = watcher2->next;
        temwat2->next = nullptr;
        return watcher1->next;
    }
};

两个哨兵节点尾插法轻松搞定