【LeetCode】C# 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.

去除给定有序链表中重复部分。
思路：运用两个指针。fast先走完重复数，后面slow（代表第一个该重复的数）next指向fast的next，如此过滤掉所有重复节点。

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     public int val;
 *     public ListNode next;
 *     public ListNode(int x) { val = x; }
 * }
 */
public class Solution {
    public ListNode DeleteDuplicates(ListNode head) {
        if(head == null || head.next == null)return head;
        ListNode FakeHead = new ListNode(0);
        FakeHead.next = head;
        ListNode fast = head;
        ListNode slow = head;
        while (fast != null){
            while(fast.next != null && fast.val == fast.next.val) 
                fast = fast.next;
            slow.next = fast.next;
            fast = fast.next;
            slow = slow.next;
        }
        return FakeHead.next;
    }
}