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

.

可以使用一个指针，也可以使用两个指针来完成，以下是两种做法

/**
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode(int x) { val = x; }
* }
*/
public class Solution {
public ListNode deleteDuplicates(ListNode head) {
if(head == null){
return null;
}

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

}
}

  

/**
* Definition for singly-linked list.
* public class ListNode {
*     int val;
*     ListNode next;
*     ListNode(int x) { val = x; }
* }
*/
public class Solution {
public ListNode deleteDuplicates(ListNode head) {
if(head == null) return head;

ListNode pre = head;
ListNode cur = head.next;

while(cur != null && pre != null){

if(cur.val == pre.val){
pre.next = cur.next;
cur = cur.next;

}else{
pre = pre.next;
cur = cur.next;
}
}
return head;

}
}