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 || head->next == NULL) return head;        ListNode dummy(-1);        dummy.next = head;        for (ListNode *prev = head, *cur = head->next; cur; cur = cur->next) {            if (prev->val == cur->val) {                prev->next = cur->next;                delete cur;            }            else                 prev = cur;        }        return dummy.next;    }};