[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 || head->next == NULL)            return head;        ListNode* p = head;        ListNode* q = p->next;        while (q != NULL)        {            if (p->val == q->val)            {                q = q->next;                p->next = q;            }            else            {                p = p->next;                q = q->next;            }        }        return head;    }};