[leetcode] Remove Duplicates from Sorted List II

最新推荐文章于 2024-01-17 14:07:10 发布

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本文介绍了一种算法，用于从已排序的链表中删除所有重复的节点，仅保留唯一的数值。

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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.

对于linklist，结尾和开头要特别注意。我的代码还得特别注意最后一个是否被处理了。有些code可以合并，减少代码量

class Solution {
public:
    ListNode *deleteDuplicates(ListNode *head) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if (head == NULL)
            return head;
            
        ListNode *pre = NULL; 
        ListNode *pivot  = head;
        ListNode *current = head;
        ListNode * newHead = NULL;
        bool first = true;
        while (current->next){
            current = current->next;
            if (current->val != pivot->val){
                if (pre==NULL){
                    if (first == true){
                        newHead = pivot;
                        pre= pivot;
                    }
                    pivot = current;
                    first = true;
                }
                else{
                    if (first == true){
                        pre->next = pivot;
                        pre = pivot;
                    }
                    pivot = current;
                    first = true;
                }
            }
            else
                first = false;
        }
        if (pre){
            if (first == true){
                pre->next = current;
                pre = current;
            }
            pre->next = NULL;
        
        }
        else{
            if (first == true)
                newHead = current;
        }
        return newHead;
    }
};