Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list. For example, Given 1->2->3->3->4->4->5, return 1->2->5. Given 1->1->1->2->3, return 2->3. http://leetcode.com/onlinejudge#question_82

leetcode_remove_duplicates_from_sorted_list_2.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* prev = NULL;
        ListNode* cur = head;
        while (cur != NULL) {
            int cnt = 0;
            int val = cur->val;
            while (cur != NULL && cur->val == val) {
                cur = cur->next;
                cnt++;
            }
            if (cnt == 1) {
                ret->val = val;
                prev = ret;
                ret = ret->next;
            }
        }
        if (prev != NULL)
            prev->next = NULL;
        else
            head = NULL;
        return head;
    }
};