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
.
/**
* 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)
return NULL;
ListNode * p1, * p2;
p1 = head;
p2 = head->next;
int currentValue = p1->val;
while (p1){
if (!p2){
p1->next = p2;
p1 = p1->next;
}
else if (p2->val==currentValue){
p2 = p2->next;
}
else{// p2 != NULL and p2->val!=currentValue
currentValue = p2->val;
p1->next = p2;
p1 = p1->next;
p2 = p1->next;
}
}
return head;
}
};