[LeetCode] Remove Duplicates from Sorted List - 链表问题

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     struct ListNode *next;
 * };
 */
struct ListNode* deleteDuplicates(struct ListNode* head) {
    struct ListNode *p,*q;
    q=head;
    if(head==NULL || head->next==NULL)        //防止[]和[1]
        return head;
    while(q) {
        if( q->next!=NULL && q->next->val==q->val ) {
            //删除操作 最后free
            p=q->next;
            q->next=p->next;
            free(p);
        }
        else {
            q=q->next;
        }
    }
    return head;
}