leetcode-83-链表题-删除排序链表中的重复元素

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题目

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解法

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/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */

// 双指针
class Solution {
public:
    ListNode* deleteDuplicates(ListNode* head) {
        if(!head || !head->next) return head;

        ListNode *a = head;
        ListNode *b = head->next;
        while(b){
            if(a->val == b->val){
                if(!b->next)
                    a->next = b->next;
                b = b->next;
            }else{
                a->next = b;
                a = a->next;
                b = b->next;
            }
        }

        return head;
    }
};

// 直接法
class Solution {
public:
    ListNode* deleteDuplicates(ListNode* head) {
        if(!head || !head->next) return head;

        ListNode *ptr{head};
        while(ptr->next){
            if(ptr->val == ptr->next->val){
                ptr->next = ptr->next->next;
            }else{
                ptr = ptr->next;
            }
        }

        return head;
    }
};