How to find highest ,second highest number, Lowest Second Lowest number in given Array

Question

Hello guys, Can anyone Please tell me how to How to find highest ,second highest number, Lowest Second Lowest number in given Array

var numbers = new[] {855,3,64,6,24,75,3,6,24,45};

Any pointer and suggestion would really helpful . Thanks

Answer 1

You don't specify the complexity requirement: one way is to sort the array in descending order and pick the top, second and third items.

Another is to build a Heap, and then perform remove root 3 times (with the heap being rebuilt after each remove).

Answer 2

Assuming you have at least 2 items in the array you can use OrderBy() and ElementAt():

var numbers = new[] { 855, 3, 64, 6, 24, 75, 3, 6, 24, 45 };
var secondLowest = numbers.OrderBy(num => num).ElementAt(1);
var secondHighest = numbers.OrderBy(num => num).Reverse().ElementAt(1);

Getting the highest and lowest is simpler and can be done using Max() and Min() LINQ methods.

var lowest = numbers.Min();
var highest = numbers.Max();

If you're worried about complexity, you can achieve better result using Selection algorithm. Using it you can perform the operations in O(n) complexity.

Answer 3

You can also try this -

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class secondHighestLowest : System.Web.UI.Page
{
    int[] arr = new int[10] { 45, 3, 64, 6, 24, 75, 3, 6, 24, 45 };

    protected void Page_Load(object sender, EventArgs e)
    {
        secondHighestLowestNumber();
        secoundLowestNumber();
    }

    private void secondHighestLowestNumber()
    {
        int firstHighestNumber = arr[0];
        int secondHighestNumber = arr[0];
        for(int i = 0; i<arr.Length; i++)
        {
            if (arr[i]>firstHighestNumber)
            {
                firstHighestNumber = arr[i];
            }
        }

        for (int x = 0; x < arr.Length; x++)
        {
            if (arr[x]>secondHighestNumber && firstHighestNumber!=arr[x])
            {
                secondHighestNumber = arr[x];
            }
        }

        Response.Write("secondHighestNumber---- " + secondHighestNumber + "</br>");
    }

    private void secoundLowestNumber()
    {
        int firstLowestNumber = arr[0];
        int secondLowestNumber = arr[0];
        for (int i = 0; i < arr.Length; i++)
        {
            if (arr[i] < firstLowestNumber)
            {
                firstLowestNumber = arr[i];
            }
        }

        for (int x = 0; x < arr.Length; x++)
        {
            if (arr[x] < secondLowestNumber && firstLowestNumber != arr[x])
            {
                secondLowestNumber = arr[x];
            }
        }

        Response.Write("secondLowestNumber---- " + secondLowestNumber + "</br>");
    }
}

Hope this is helpful :)