LeetCode OJ: Remove Linked List Elements

题目：

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代码：

/** * Definition for singly-linked list. * struct ListNode { *     int val; *     ListNode *next; *     ListNode(int x) : val(x), next(NULL) {} * }; */class Solution {public:    ListNode* removeElements(ListNode* head, int val) {    ListNode *p = head, *pre_p = head;;        while (p != NULL)        {            if (p->val == val){                if (p == head)  //指针p与head在同一节点上，由于该节点要销毁，则head需后移                {                    head = head->next;                    //delete p;                    //p = head;                }                if (pre_p == p) //pre_p与p也指向同一节点                {                    delete p;                    pre_p = p =head;                }                else{           //pre_p指向p的前一节点                    pre_p->next = p->next;                    delete p;                    p = pre_p->next;                }            }            else            {                if (pre_p = p){                    p = p->next;                }                else                {                    pre_p = p;                    p = p->next;                }            }        }        return head;    }};

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运行结果：
Accepted 32ms

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代码图例分析：