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

Example

Given: 1 --> 2 --> 6 --> 3 --> 4 --> 5 --> 6, val = 6

Return: 1 --> 2 --> 3 --> 4 --> 5

 

 

/** * Definition for singly-linked list. * struct ListNode { *     int val; *     ListNode *next; *     ListNode(int x) : val(x), next(NULL) {} * }; */  /* 解题思路： 要分为val 在头，在尾，在链表中间 新建一个头结点，使得链表有以一个空节点为头，然后只需要考虑链表中间和链表尾部的两种情况  */ class Solution {public:    ListNode* removeElements(ListNode* head, int val) {        if(head == NULL)            return head;                ListNode* tempHead = new ListNode(0);        tempHead->next = head;        ListNode* pre = tempHead;        ListNode* cur = head;                while(cur){            if(cur->val == val && cur->next != NULL){                ListNode* ptr = cur;                cur = cur->next;                pre->next = ptr->next;                free(ptr);            }            else if(cur->val == val && cur->next == NULL){                cur = cur->next;                pre->next = cur;            }            else {                pre = pre->next;                cur = cur->next;            }            }                return tempHead->next;    }};