[leetcode 82] Remove Duplicates from Sorted List II

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#链表

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本文介绍如何在保持链表排序的情况下，移除所有重复的节点，仅保留唯一的数值。通过实例演示了如何实现这一功能，涉及链表操作及算法优化。

Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.

For example,
Given 1->2->3->3->4->4->5, return 1->2->5.

Given 1->1->1->2->3, return 2->3.

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode *deleteDuplicates(ListNode *head) {
        if (head == NULL || head->next == NULL) {
            return head;
        }
        ListNode dummy(-1);
        auto prev = &dummy;
        auto cur = head;
        while (cur) {
            bool dup = false;
            while (cur->next != NULL && cur->val == cur->next->val) {
                dup = true;
                auto tmp = cur->next;
                cur->next = cur->next->next;
                delete tmp;
            }
            if (dup) {
                auto tmp = cur;
                cur = cur->next;
                delete tmp;
                continue;
            }
            prev->next = cur;
            prev = prev->next;
            cur = cur->next;
        }
        prev->next = cur;
        return dummy.next;
    }
};