在我的课堂上，我必须创建一种方法来查找数组C＃中的多个最大数

Question

In my class i have to create a method that will find multiple maximum numbers within an array. the user will input how many maximum numbers they are wanting and then the code should display all those numbers. if i select 2 this code will show me the 2 maximum numbers but if im wanting more it just doesnt work. i was trying to search the array for the maximum number and then have it display the outcome and then change that element to 0 and than repeat the loop until it hits that number (userinput). im soo frustrated can someone help me please

    public static int FindingMaxNum(int[] arr, int max)
    { 
        int userinput;
        Console.Write("Enter the number of maximum values: ");
        userinput = Convert.ToInt32(Console.Read());

        int i = 0;
        int c = 0;
        for (i = 0; i < arr.Length; i++)
        { 
         if (arr[i] >= max)
         {
             max = arr[i];
             c++;

             while (c <= userinput)
             {
                Console.WriteLine(max);
                arr[i] = 0;
                break;
             }
          }

        }
        return -1;
     }

Answer 1

Simple solution with average complexity O(nlogn): Sort the array first then print the last N nos.

 int[] arr = new int[]{-5,-69,1250,24,-96,32578,11,124};
   Array.Sort(arr);
   int n=3;
   for(int i=arr.Length-1;i>=0 && n>0 ;--i){
       n--;
    Console.WriteLine(arr[i]);
   }

Now coming to your code, there are multiple problems. First there is no need to take 'max' as parameter in your function. Second you are looping only arr.Length times once. There should be nested loop, outer one of which has to run userInput times and inner on has to iterate over all the values. Third you should initialize to extracted value position to minimum value so that the method works for negative numbers too.

Refined code:

 for(int i=0;i<userinput;++i){
        int max = int.MinValue,pos=-1;
        for(int j=0;j<arr.Length;++j){
            if(max<arr[j]){
                pos = j;
                max = arr[j];
            }
        }
        arr[pos] = int.MinValue;
        Console.Write(max+",");
    }

Answer 2

If I understand correctly, you want to get some number of items from an array whose values are greater than all the others in the array.

If so, something like this modified version of your method may do the trick:

public static void WriteMaxNum(int[] arr)
{
    if (arr == null)
    {
        Console.WriteLine("The array is null");
        return;
    }

    if (arr.Length == 0)
    {
        Console.WriteLine("The array is empty");
        return;
    }

    int count = arr.Length;
    int numMaxValues;

    // Get number of max values to return from user
    do
    {
        Console.Write("Enter the number of maximum values (1 - {0}): ", count);
    } while (!int.TryParse(Console.ReadLine(), out numMaxValues) ||
             numMaxValues < 1 ||
             numMaxValues > count);

    // Output the max values
    Console.Write("The {0} max values are: ", numMaxValues);
    Console.WriteLine(string.Join(", ", arr.OrderByDescending(i => i).Take(numMaxValues)));
}

Usage

static void Main(string[] args)
{
    var myArray = new[] { 1, 9, 4, 8, 2, 5, 0, 7, 6, 3 };
    WriteMaxNum(myArray);

    Console.Write("\nDone!\nPress any key to exit...");
    Console.ReadKey();
}

Output