基于子列表对列表列表进行排序的方法

Question

我有一个由int数组组成的列表列表：

(List<List<int[]>>)

我想根据列表int第一个元素中数组中的第一个索引对列表列表进行排序。到目前为止，我的解决方案是：

List<List<int[]>> myList = new List<List<int[]>> { new List<int[]> { new int[] { 1, 5 }, new int[] { 2, 4 } }, new List<int[]> { new int[] { 3, 4 }, new int[] { 0, 1 } } };myList.OrderByDescending(x => x.Max(y => y[0])).ToList();

结果是第二个列表排在第一位，第一个排在第二位。

但我不喜欢那个，因为性能是一个关键点，我不喜欢执行这个Max操作，因为它没用。

那么，有没有更好的办法呢？

——

编辑：我完成了使用：

myList.OrderByDescending(x => x[0][0]).ToList();

正如 CodeCaster 在评论中提出的那样。这个在我的代码中比 Aldert 提出的选项更快。但他的回答也值得一看。

Answer 1

此代码根据您传递给比较器的顺序对 asc 或 desc 进行排序。它在元素上运行 O*1，以设置能够进行比较的结构。我很想知道它是否适合你更快（我认为只适用于非常大的树）。当您已经对所有内部列表进行排序时，您不需要保留帮助字典，然后您可以取最后一个元素。using System;using System.Collections.Generic;namespace ConsoleApp1{class Program&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; static void Main(string[] args)&nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; List<List<int>> mainList = new List<List<int>>();&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; List<int> newList = new List<int>();&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Random rand = new Random();&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; for (int i = 0; i < 30; i++)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; int ra = rand.Next(200);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if (i % 5&nbsp; == 0)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if (newList.Count > 0)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; newList = new List<int>();&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; mainList.Add(newList);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; newList.Add(ra);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; mainList.Sort( new MaxComparer(mainList, false));&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; foreach (List<int> oneL in mainList)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; foreach (int oneInt in oneL)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Console.Write(oneInt + " ");&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Console.WriteLine();&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; public class MaxComparer : IComparer<List<int>>&nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; bool order = false;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Dictionary<int, int> helper = new Dictionary<int, int>();&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; public MaxComparer(List<List<int>> sortList, bool Order)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; order = Order;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; foreach (List<int> oneL in sortList)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; int max = int.MinValue;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; foreach (int oneInt in oneL)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if (max < oneInt) max = oneInt;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; helper.Add(oneL.GetHashCode(), max);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; public int Compare(List<int> x, List<int> y)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; return helper[x.GetHashCode()].CompareTo(helper[y.GetHashCode()]) * (order ? 1:-1);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; }}

Answer 2

这是您通过二进制比较寻找的答案，它相当简单，因为它从 sublint 和数组中取出第一个元素（正如您所寻找的那样）。using System;using System.Collections.Generic;namespace ConsoleApp1{&nbsp; &nbsp; class Program&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; static void Main(string[] args)&nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; List<List<int[]>> mainList = new List<List<int[]>>();&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Random rand = new Random();&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; for (int i = 0; i < 30; i++)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; List<int[]> subList = new List<int[]>();&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; int limj = rand.Next(5);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; for (int j = 0; j < 5 + limj; j++)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; int limk = rand.Next(5);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; int[] arrayInt = new int[limk + 5];&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; for (int k = 0; k < limk + 5; k++)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; arrayInt[k] = rand.Next(200);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; subList.Add(arrayInt);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; mainList.Add(subList);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; mainList.Sort(new MaxComparer(false));&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; foreach (List<int[]> oneL in mainList)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; foreach (int[] arrayList in oneL)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; foreach (int i in arrayList) Console.Write(i + " ");&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Console.Write("|");&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Console.WriteLine();&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; public class MaxComparer : IComparer<List<int[]>>&nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; bool order = false;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; public MaxComparer(bool Order)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; order = Order;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; public int Compare(List<int[]> x, List<int[]> y)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; return x[0][0].CompareTo(y[0][0]) * (order ? 1 : -1);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; }}

Answer 3

这是你想要的？&nbsp;var&nbsp;sortedList&nbsp;=&nbsp;myList.OrderBy(x&nbsp;=>&nbsp;x.Select(y&nbsp;=>&nbsp;y.Select(z&nbsp;=>&nbsp;z).OrderBy(z&nbsp;=>&nbsp;z))).ToList();编辑：我忘了深入一层。导致该错误的原因是它想要对数组对象而不是其元素进行排序。