see-83. Remove Duplicates from Sorted List

移除链表中的重复元素：设置二个指针begin&&end，间距为1；如果begin与end对应的属性值相同，则删掉end对应的元素并后移一位；否则，同时后移一位；

/**
 * 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 *begin=head;
        ListNode *end=NULL;
        if(head!=NULL)
            end=head->next;
        else
            return head;
        
        
       while(end!=NULL)
       {
          if(end->val==begin->val)
          {
              begin->next=end->next;
              end=end->next;
          }
            else
            {
                begin=begin->next;
                end=end->next;
            }
            
        }
        return head;
    }
};