[LeetCode] Remove Duplicates from Sorted List

最新推荐文章于 2022-04-03 22:46:44 发布

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本文介绍了一种在有序链表中删除重复元素的方法。通过使用虚拟头节点简化边界条件处理，并利用双指针技巧实现遍历过程中直接删除重复节点的功能。此算法确保每个元素仅出现一次。

Given a sorted linked list, delete all duplicates such that each element appear only once.

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

有序链表中删除重复元素

保存前一个元素指针，若当前元素等于前一元素，跳过当前元素，

否则，前一元素指针的next指向当前元素，更新前一元素的指针为当前元素

/**
 * 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) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        ListNode *dummy = new ListNode(-1);
        ListNode *cur = head;
        ListNode *pre = NULL;
        ListNode *dp = dummy;
        while(cur != NULL) {
            if(pre == NULL) {
                dp->next = cur;
                pre = cur;
                cur = cur->next;
                dp = dp->next;
            }
            else {
                if(pre->val == cur->val) {
                    cur = cur->next;
                }else {
                    dp->next = cur;
                    pre = cur;
                    cur = cur->next;
                    dp = dp->next;
                }
            }
        }
        dp->next = NULL;
        return dummy->next;
    }
};