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

【分析】頭結點放到最後來刪除，先儲存要刪除節點前面一個節點，然後再刪除。
程式碼如下：

struct ListNode* removeElements(struct ListNode* head, int val)
{
    if
 
(!head)
        return NULL;

    struct ListNode* curTemp = head;/*當前要處理的節點*/
    struct ListNode* nextTemp = head->next;

    /*1.處理頭結點以外的結點*/
    while(nextTemp) {

        if(val == nextTemp->val) {
            curTemp->next = nextTemp->next;
            free(nextTemp);
            nextTemp =
 
 curTemp->next;
            continue;
        }

        nextTemp = nextTemp->next;
        curTemp = curTemp->next;
    }
    /*2.處理頭結點*/
    if(head->val == val) {
        curTemp = head;
        head = head->next;
        free(curTemp);
    }

    return head;
}