No203_ListNode.cs

using LeetCode.ExtensionFunction;
using System;
using System.Collections.Generic;
using System.Text;

namespace LeetCode_203
{
    //static void Main(string[] args)
    //{
    //    var solution = new Solution();
    //    while (true)
    //    {
    //        //int input = int.Parse(Console.ReadLine());
    //        //int input2 = int.Parse(Console.ReadLine());
    //        //string input = Console.ReadLine();
    //        //string input2 = Console.ReadLine();
    //        //int[] intArr = input.Split(',').Select(s => int.Parse(s)).ToArray();
    //        //int input2 = int.Parse(Console.ReadLine());
    //        var builder = new DataStructureBuilder();
    //        //int?[] data = new int?[] { 10, 5, 15, null, null, 6, 20 };
    //        //int?[] data = new int?[] { 6, 2, 8, 0, 4, 7, 9, null, null, 3, 5 };
    //        //int?[] data = new int?[] { -2147483648, null, 2147483647 };
    //        //int?[] data = new int?[] { 1, 3, null, null, 2 };
    //        //var tree = builder.BuildTree(data);
    //        var listNode = builder.BuildListNode(new int[] { 4, 2, 4, 1, 1, 1 });
    //        //var listNode2 = builder.BuildListNode(new int[] { 5, 6});
    //        //listNode2.next.next = listNode.next.next.next.next;
    //        var res = solution.RemoveElements(listNode, 1);
    //        ConsoleX.WriteLine(res);
    //    }
    //}

    public class Solution
    {
        /// <summary>
        /// 第一反应解
        /// 时间复杂度：O(n)
        /// 空间复杂度：O(1)
        /// sentinel(哨兵)
        /// </summary>
        /// <param name="head"></param>
        /// <param name="val"></param>
        /// <returns></returns>
        public ListNode RemoveElements(ListNode head, int val)
        {
            var sentinel = new ListNode(-1);
            sentinel.next = head;
            //打工仔，穿着head衣服的temp
            head = sentinel;
            while (head != null)
            {
                //如果下一个节点的值等于目标值，则跳过这个节点
                if (head.next != null && head.next.val == val)
                    head.next = head.next.next;
                else
                    head = head.next;
            }
            return sentinel.next;
        }
    }
}