C# sorting from chosen # nearest to farthest

Question

using System.Linq;

        int min = 1;
        int max = 100;
        int[] a = new int[10];
        Random randNum = new Random();
        for (int i = 0; i < a.Length; i++)
        {
            a[i] = randNum.Next(min, max);
        }
        int t;
        Console.WriteLine("array :");
        foreach (int aa in a)
            Console.Write(aa + " ");
        Console.Write("\n");
        Console.WriteLine("Chosen number");
        {... }
            a = a.OrderBy(e => Math.Abs(e, b));
        foreach (var b in a) Console.Write("{0} ", x);
        {
            int b = int.Parse(Console.ReadLine());


            {
                for (int p = 0; p <= a.Length - 2; p++)
                {
                    for (int i = 0; i <= a.Length - 2; i++)
                    {
                        if (a[i]> a[i + 1])
                        {
                            t = a[i + 1];
                            a[i + 1] = a[i];
                            a[i] = t;

                        }

                    }
                }
                Console.Write("\n");
                Console.WriteLine("\n" + "+ :");
                foreach (int aa in a)
                    Console.Write(aa + " ");
                Console.Write("\n");
            }

This is Code I tried to use. but what I want to do is choosing certain number and sort nearest to farthest from the chosen number. For example there are 7, 5, 3, 2, 9 in array, and let's say I choose 5 from the array. Then the result should come out 5 7 3(order doesn't matter)2 9. Help me plz I am very noob TnT

https://stackoverflow.com/questions/20186681/how-to-move-specific-item-in-array-list-to-the-first-item — Manish Kumar, Mar 29 '18 at 04:43

score 1 · Answer 1 · answered Mar 29 '18 at 04:37

1

Change condition (a[i] > a[i + 1]) to compare difference between (a[i] and b) and (a[i+1] and b)

answered Mar 29 '18 at 04:37

Backs

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https://stackoverflow.com/questions/20186681/how-to-move-specific-item-in-array-list-to-the-first-item – Manish Kumar Mar 29 '18 at 04:40
i don't get what you are saying can you help me more specifically? – 장재현 Mar 29 '18 at 04:46
@장재현 what problem do you have? Just replace comparison of array item to comparison of difference between array item and number – Backs Mar 29 '18 at 04:58
do I have to keep useing if? or delete if to compare?? – 장재현 Mar 29 '18 at 04:59

Richard Schneider · Answer 2 · 2018-03-29T05:14:57.853

0

You want to sort the array by the distance between the array element and the chosen number. Assuming that a is an array of numbers and b is the chosen number,

then replace for (;;) { ... } with this

using System.Linq;

a = a.OrderBy(e => (int) Math.Abs(e - b)).ToArray();
foreach (var x in a) Console.Write("{0} ", x);

edited Mar 29 '18 at 05:14

answered Mar 29 '18 at 04:59

Richard Schneider

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as you said I came to here but it still giving me errors. Plz help me more – 장재현 Mar 29 '18 at 05:07

Zohar Peled · Answer 3 · 2018-03-29T05:39:58.303

Well, it took me some tome to understand what kind of sort you wanted, and then I've looked at your code and it seems to me you got your self into an over complicated method, so I've decided I'm not going to try and help you with your own code but write the entire sort from scratch.

I ended up with a method that uses an auxiliary array but only use a single loop to get the order done:

void StrangeSort(int[] arr, int num)
{
    var index = Array.IndexOf(arr, num);
    if(index > -1)
    {
        var copy = new int[arr.Length];
        int copyIndex = 0, 
            down = index-1, 
            up = index+1;
        copy[copyIndex] = arr[index];
        while(down > -1 || up < arr.Length)
        {
            if(down > -1)
            {
                copyIndex++;
                copy[copyIndex] = arr[down];
                down--;
            }
            if(up < arr.Length)
            {
                copyIndex++;
                copy[copyIndex] = arr[up];
                up++;
            }
        }
        copy.CopyTo(arr, 0);
    }
}

You can see a live demo on rextester.

And of course, there's always linq:

var index = Array.IndexOf(arr, num); // arr being your array, num being the value selected

arr = arr.Select((v, i) => new {Value = v, Index = i})
        .OrderBy(e => Math.Abs(index - e.Index))
        .Select(e => e.Value)
        .ToArray();

C# sorting from chosen # nearest to farthest

3 Answers3