leetcode 83 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.



下面是我的解决方案，考虑测试用例：

1，1

1，1，1

1，2，2

/**
* 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* pre = head;
ListNode* cur = head->next;

while(cur!=NULL)
{
if(cur->val==pre->val)
{
pre->next = pre->next->next;
cur = cur->next;
if(cur==NULL)return head;
//free(cur)没有free是不对的，可能引起内存泄漏;
}
else if(cur->val!=pre->val)
{
pre = pre->next;
cur = cur->next;
}

}
return head;

}
};

c++：

public class Solution {
public ListNode deleteDuplicates(ListNode head) {
if (head == null) return head;

ListNode cur = head;
while(cur.next != null) {
if (cur.val == cur.next.val) {
cur.next = cur.next.next;
}
else cur = cur.next;
}
return head;
}
}

c语言：

struct ListNode* deleteDuplicates(struct ListNode* head)
{
if (head) {
struct ListNode *p = head;
while (p->next) {
if (p->val != p->next->val) {
p = p->next;
}
else {
struct ListNode *tmp = p->next;
p->next = p->next->next;
free(tmp);//这块在实际代码中，非常有必要
}
}
}

return head;

}

简洁的python解决方案：

class Solution:
# @param head, a ListNode
# @return a ListNode
def deleteDuplicates(self, head):
node = head
while node:
while node.next and node.next.val == node.val:
node.next = node.next.next

node = node.next

return head