【leetcode】83. Remove Duplicates from Sorted List

采用两个指针，一个指向不重复的前结点，一个指向当前结点，当出现值不同的node结点时，前结点移动到当前结点。注意当前结点指向链表尾时，也需要更新前结点到的后继到链表尾。

/**
 *  @author         johnsondu
 *  @time           10:18 12th Oct 2015
 *  @type           remove nodes from list
 *  @status         Accepted
 *  @problem        Remove Duplicates from Sorted List
 *  @url            https://leetcode.com/problems/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) {
        if(head == NULL) return head;
        ListNode* cur = head;
        ListNode* pre = head;
        int val = cur->val;
        while(1)
        {
            cur = cur->next;
            if(cur == NULL) {
                pre->next = cur;
                break;
            }
            if(cur->val != val) {
                val = cur->val;
                pre->next = cur;
                pre = cur;
            }
        }
        return head;
    }
};