/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 * };
 */
/**
 * 代码中的类名、方法名、参数名已经指定,请勿修改,直接返回方法规定的值即可
 *
 * 
 * @param head ListNode类 
 * @return ListNode类
 */
struct ListNode* deleteDuplicates(struct ListNode* head ) 
{
    if(head == NULL)
    {
        return head;
    }
    struct ListNode* fast=head->next;
    struct ListNode* slow=head;
    while(fast != NULL)
    {
	  	//如果两个结点的值相等
        if(fast->val == slow->val)
        {
            slow->next=fast->next;
            free(fast);
            fast=slow->next;
        }
        else //如果不相等
        {
        fast=fast->next;
        slow=slow->next;
        }
    }
    
    return head;
}