Remove Duplicates from Sorted List

Desicription

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.

Solution

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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) {
        ListNode* now = head;
        while(now){
            while(now->next && now->val == now->next->val){
                ListNode* tmp = now->next;
                now->next = tmp->next;
                free(tmp);
            }
            now = now->next;
        }
        return head;
    }
};