LeetCode (Remove Duplicates from Sorted List II)

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本文介绍了一种从有序链表中移除所有重复元素的方法，只保留唯一元素，通过一个示例展示了算法实现过程。

Problem;

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.

Solution:

/**
 * 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 || !head->next) return head;
        ListNode l(0), *p = &l;
        ListNode *pre = head, *cur = head->next;
        if(pre->val != cur->val){
            p->next = pre;
            p = p->next;
        }
        while(cur){
            if(pre->val != cur->val && (!cur->next || cur->val != cur->next->val)){
                p->next = cur;
                p = p->next;
            }
            pre = cur;
            cur = cur->next;
        }
        p->next = NULL;
        return l.next;
    }
};