Remove Duplicates from Sorted List

/**
 * 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) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if (!head) return NULL;
        
        ListNode *prev = head, *cur = prev->next;
        
        while (cur)
        {
            if (prev->val == cur->val)
            {
                prev->next = cur->next;
                delete cur;
                cur = prev->next;
            }
            else
            {
                prev = cur;
                cur = cur->next;
            }
        }
        return head;
    }
};