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. http://leetcode.com/onlinejudge#question_83

leetcode_remove_duplicates_from_sorted_list.cpp

/**
 * 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* ret = head;
        ListNode* cur = head;
        ListNode* prev = NULL;
        while (cur != NULL) {
            if (cur->next == NULL || cur->val != cur->next->val) {
                ret->val = cur->val;
                prev = ret;
                ret = ret->next;
            }
            cur = cur->next;
        }
        if (prev != NULL)
            prev->next = NULL;
        return head;
    }
};