leetcode 083 Remove Duplicates from Sorted List

原创于 2016-05-07 23:14:15 发布 · 351 阅读

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本文介绍了一种从已排序链表中删除所有重复元素的方法，确保每个元素仅出现一次。通过示例1->1->2和1->1->2->3->3展示了预期效果，并提供了完整的C++实现。

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.

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/**
 * 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) return head;
		ListNode *pre=head, *cur=NULL, *ret=NULL, *retCur=NULL;

		for(cur=head->next; cur!=NULL; cur=cur->next) {
			if(cur->val != pre->val){
				if(ret==NULL) {
					ret = pre;
				} else {
					retCur->next = pre;
				}
				retCur = pre;
				retCur->next=NULL;
			}
			pre=cur;
		}

		if(ret==NULL) {
			ret = pre;
		} else {
			retCur->next = pre;
		}
		retCur = pre;
		retCur->next=NULL;

		return ret;
    }
};