83. 删除排序链表中的重复元素

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     struct ListNode *next;
 * };
 */

/*思路:先建立一个带头结点的空链表,然后先插入第一个元素,然后再比较旧链表和新链表的元素值,不同再插入,
也可以把不同的值都放入一个数组，然后再根据数组建表
*/
struct ListNode* deleteDuplicates(struct ListNode* head){
    struct ListNode * h1 = (struct ListNode * )malloc(sizeof(struct ListNode)),*tail;
    h1->next = NULL;
    tail = h1;
    int count = 0;
    while(head)
    {
       //if(head->val != head->next->val)这句到了最后一个节点就会出错
        if(count==0)
        {
             struct ListNode * h2 = (struct ListNode * )malloc(sizeof(struct ListNode));
             h2->val = head->val;
             h2->next = NULL;
             tail->next = h2;
             tail = h2;
            count++;
        }else{
            if(tail->val!=head->val){
                struct ListNode * h2 = (struct ListNode * )malloc(sizeof(struct ListNode));
             h2->val = head->val;
             h2->next = NULL;
             tail->next = h2;
             tail = h2;
            }
        }
         head = head->next;
    }

    return h1->next;
}