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.

LL基本操作：每次判断p.val与p.next.val是否相等，若相等则直接连接下一个node，若相等则移后指针。

var deleteDuplicates = function(head) {
    if(!head)
        return null
    var dummy = new ListNode()
    dummy.next = head
    var p = head
    while(p.next)
        if(p.val===p.next.val)
            p.next = p.next.next
        else
            p = p.next
    return dummy.next
}