83. Remove Duplicates from Sorted List

Given a sorted linked list, delete all duplicates such that each element appear only once.

这个题目采用了两种方法，一种递归，一种循环，其实原理都差不多。就是一个个找下一个的值是否和当前节点的值相同，若相同则删除，若不同，则继续检查下一个节点。

//方法一var deleteDuplicates = function(head) {    if(head==null || head.next==null)return head;    if(head.val==head.next.val){        var temp=head.next.next;        //delete head.next;        head.next=temp;        deleteDuplicates(head);    }    else deleteDuplicates(head.next);    return head;}// 方法二var deleteDuplicates = function(head) {    var temp=new ListNode(head.val);    temp=head;    while(temp && temp.next){        if(temp.next.val==temp.val){            var de=temp.next.next;            delete temp.next;            temp.next=de;        }        else temp=temp.next;    }    return head;}