Leetcode#83Remove 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.

分析，删除重复项，每个元素只出现一次，这里使用hash函数，判断节点值是否出现过

public class Solution {

public ListNode deleteDuplicates(ListNode head) {

Map<Integer,Integer> x=new HashMap<Integer,Integer>();

ListNode H=new ListNode(0);

H.next=head;

ListNode p=H;

while(p.next!=null)

{

if(x.get(p.next.val)==null)

{

x.put(p.next.val,1);

p=p.next;

}

else

{

p.next=p.next.next;

}

}

return H.next;

}

}