Question

如何将数组切片分配给新数组。我试图将最大连续的相等元素分配给一个新数组。

我认为我有正确的基本逻辑，但无法切换到新数组。这是Arrays中的练习4 - 使用c＃进行计算机编程的基础知识。

using System;
using System.Collections.Generic;

class ArrayEx4
{
    static void Main()
    {
        int[] testArray = { 1, 1, 2, 3, 2, 2, 2, 1 }; // Output wanted {2,2,2};

        int count = 0;
        int bestCount = 0;
        int startArray = 0;
        int endArray = 0;
        int first = 0;
        for (int i = 0; i < testArray.Length; i++)
        {
            if (testArray[i] == testArray[i+1])
            {
                count += 1;
                i = first;
                if (count > bestCount)
                {
                    count = bestCount;
                    startArray = first;
                    endArray = first + bestCount;
                }
            }
            int[] bestArray = testArray.Slice(startArray, endArray);
            Console.WriteLine("The best array is  {0}", bestArray);
        }

    }
}

我收到指令错误，所以我添加了System.Collections.Generic;但我仍然遇到这个错误。

C:\Users\Sayth\Documents\Scripts>csc ArrayEx4.cs
Microsoft (R) Visual C# Compiler version 4.0.30319.33440
for Microsoft (R) .NET Framework 4.5
Copyright (C) Microsoft Corporation. All rights reserved.

ArrayEx4.cs(28,32): error CS1061: 'System.Array' does not contain a definition
        for 'Slice' and no extension method 'Slice' accepting a first argument
        of type 'System.Array' could be found (are you missing a using directive
        or an assembly reference?)

修改

我上面的解决方案中的逻辑从未起作用。以下是更新后的代码，包括以下答案。

using System;
using System.Linq;

class Arr4
{
    static void Main()
    {
        int[] testArray = { 1, 1, 2, 3, 2, 2, 2, 1 }; // Output wanted {2,2,2};
        int count = 0;
        int bestCount = 0;
        int start = 0;
        int a = 0;

        for(int i = 0; i < testArray.Length -1; i++)
        {
            while (testArray[i] == testArray[a])
            {
                count += 1;
                a += 1;
                if (count > bestCount)
                {
                    start = i;
                    bestCount = count;
                }
            }
        }

     int end = bestCount + start;
     Console.WriteLine("The start is {0} and count is {1}", start, bestCount);
     var bestArray = testArray.Skip(start)
                      .Take(end - start)
                      .ToArray();
        Console.Write("{ ");
        Console.Write(string.Join(", ", bestArray));
        Console.Write(" }");
    }   

}

Answer 1

使用Linq你可以这样做：

var bestArray = testArray.Skip(startArray) 
                         .Take(endArray - startArray)
                         .ToArray();

（不要忘记添加using System.Linq）

Answer 2

在c＃中，您不需要手动遍历数组，只需使用LINQ。

这将为您完成工作：）

int[] testArray = { 1, 1, 2, 3, 2, 2, 2, 1 }; // Output wanted {2,2,2};

int[] maxSequence = testArray.Select((n, i) => new { Value = n, Index = i})
    .OrderBy(s => s.Value)
    .Select((o, i) => new { Value = o.Value, Diff = i - o.Index } )
    .GroupBy(s => new { s.Value, s.Diff})
    .OrderByDescending(g => g.Count())
    .First()
    .Select(f => f.Value)
    .ToArray();

Answer 3

从 C＃8.0 开始，您可以使用Range类来制作数组切片。

int[] testArray = { 1, 1, 2, 3, 2, 2, 2, 1 };
int[] output = testArray[4..7]; // {2, 2, 2} // Note that end of range (7) is exclusive

有关详情，请参见docs

Array Slice创建新数组

3 个答案: