[LeetCode] Remove Duplicates from Sorted List

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.

顺序扫描一遍即可，注意释放被删除的结点的空间。

/**
 * 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) {
        // IMPORTANT: Please reset any member data you declared, as
        // the same Solution instance will be reused for each test case.
        if(head == NULL)
            return NULL;
            
        ListNode *last = head, *current = head -> next, *tmp = NULL;
        while(current != NULL)
        {
            while(current != NULL && current -> val == last -> val)
            {
                tmp = current;
                current = current -> next;
                delete tmp;
            }
            
            last -> next = current;
            last = current;
            
            if(current != NULL)
                current = current -> next;
        }
        
        return head;
    }
};