#452 Remove Linked List Elements

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题目描述：

Remove all elements from a linked list of integers that have value val.

Have you met this question in a real interview?

Yes

Example

Given 1->2->3->3->4->5->3, val = 3, you should return the list as1->2->4->5

题目思路：

这题用上dummy head，轻松可解。

Mycode（AC = 27ms）：

/** * Definition for singly-linked list. * struct ListNode { *     int val; *     ListNode *next; *     ListNode(int x) : val(x), next(NULL) {} * }; */class Solution {public:    /**     * @param head a ListNode     * @param val an integer     * @return a ListNode     */    ListNode *removeElements(ListNode *head, int val) {        // Write your code here        ListNode *dummy = new ListNode(0);        dummy->next = head;                ListNode *ptr = dummy;        while (ptr->next) {            // if ptr->next is val, then link ptr            // to ptr->next->next, ptr still stays            if (ptr->next->val == val) {                ptr->next = ptr->next->next;            }            else {// ptr goes next                ptr = ptr->next;            }        }                return dummy->next;    }};

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