Remove Duplicates from Sorted List II
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.
分析： 为了便于管理头指针，创建一个新的头指针，利用几个新的变量来判断cur和prev的关系
/**
* 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* start = new ListNode();
start->next = head; ListNode* cur = head;
ListNode* prev = start;
while(cur){
while(cur->next && cur->next->val == prev->next->val)
cur = cur->next;
if(prev->next == cur)
prev = cur;
else
prev->next = cur->next;
cur = cur->next;
}
return start->next;
}
};