C# 字典转换成list 排序后 修改其数据 效率对比

        public List<TreeNode> CreateTree(Dictionary<int, TreeNode> dic)
        {
            var list = new List<TreeNode>();
            foreach (var pair in dic)
            {
                var pid = pair.Value.ParentId;
                if (pid == 0)
                {
                    list.Add(pair.Value);
                    continue;
                }
                if (dic.ContainsKey(pid))
                {
                    var children = (List<TreeNode>)dic[pid].children;
                    children.Add(pair.Value);
                }
            }


            Stopwatch sw = new Stopwatch();


            //虽然效率最高  但是未改到本身的数据
            sw.Start();
            var list2 = dic.Select(c => c.Value).OrderByDescending(c => c.Level).Select(c =>
            {
                SetType(c);
                return 1;
            });
            sw.Stop();
            Console.WriteLine("Select:" + sw.ElapsedMilliseconds);


            sw.Restart();
            var list3 = dic.Select(c => c.Value).OrderByDescending(c => c.Level).ToList();
            list3.ForEach(c =>
            {
                SetType(c);
            });
            sw.Stop();
            Console.WriteLine("ToList Behand ForEach:" + sw.ElapsedMilliseconds);


            sw.Restart();
            var list4 = dic.Select(c => c.Value).OrderByDescending(c => c.Level);
            foreach (var c in list4)
            {
                SetType(c);
            }
            sw.Stop();
            Console.WriteLine("foreach:" + sw.ElapsedMilliseconds);

            return list;
        }