题解 | #删除有序链表中重复的元素-I#

主要思路：创建一个虚拟头结点，作为前驱节点。依次遍历链表，如果前驱节点和当前节点的值不相等，就将当前节点的值删除掉。直接都进行下移

/**
 * struct ListNode {
 *  int val;
 *  struct ListNode *next;
 * };
 */

class Solution {
  public:
    /**
     *
     * @param head ListNode类
     * @return ListNode类
     */
    ListNode* deleteDuplicates(ListNode* head) {
        ListNode* dummyhead = (ListNode*)malloc(sizeof(ListNode));
        dummyhead->next = head;
        dummyhead->val = 101;
        ListNode* pre = dummyhead, *cur = head,*t=NULL;
        while (cur != NULL) {
            if (cur->val == pre->val) {
                t=cur->next;
                pre->next = t;
                free(cur);
                cur = t;
            } else {
                pre = cur;
                cur = cur->next;
            }
        }
        return dummyhead->next;
    }
};