【LeetCode】83. Remove Duplicates from Sorted List

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.

/**
 * 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* ptr = head;
        while(head)
        {
            if(!head->next) return ptr;
            if(head->next && (head->val == head->next->val))
            {
                ListNode* del = head->next;
                head->next = del->next;
                delete del;
            }
            if(head->next && (head->val != head->next->val))
                head = head->next;
        }
        return ptr;
    }
};