题解 | #删除有序链表中重复的元素-II#

/**
 * 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 ) {
    // write code here
    if (head == NULL || head->next == NULL)
        return head;
    struct ListNode* dummy = (struct ListNode*)malloc(sizeof(struct ListNode));
    dummy->next = head;
    struct ListNode* pre = dummy;
    struct ListNode* cur = head;
    while (cur != NULL && cur->next != NULL) {
        if (cur->val != cur->next->val) {
            pre = pre->next;
            cur = cur->next;
        } else {
            while (cur->next != NULL && cur->val == cur->next->val)
                cur = cur->next;
            pre->next = cur->next;
            cur = cur->next;
        }
    }
    return dummy->next;
}