Check if all elements from one array are in the second array c#

Question

How can I check if all the elements from one array are in another array? I have a 2d array with 3 arrays in it,and I want to check all of those 3 arrays if they have all the elements from allnumbers. array1=allnumbers ? array2=allnumbers ? array1=allnumber2 ? I need to return true if at least one contains all the elements from allnumbers. I have the code bellow,but I need it not to contain more than 3 control flow statements.

// int[,][] array = {array1, array2, array3}
static bool CheckLine(int[,][] array)
        {
            const int maxL = 9;
            bool result = false;
            int[] allnumbers = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
            foreach (var singlearray in array)
            {
                int[] arr = singlearray;
                int p = 0;
                foreach (var num in allnumbers)
                {
                    foreach (var arraynumber in singlearray)
                    {
                        if (arraynumber == num)
                        {
                            p++;
                        }
                    }

                    if (p == maxL)
                    {
                        result = true;
                        break;
                    }
                }
            }

            return result;
        }

Have you tried to use Except method? Please, also share the int[,][] array sample — Pavel Anikhouski
– Pavel Anikhouski, Commented Mar 27, 2020 at 15:04

O. Jones · Accepted Answer · 2020-03-27 14:55:02Z

2

If the values in your array are unique, and you don't care about the order they're in, this is a job for HashSet. (In other words, if your arrays contain sets of numbers you can treat them as sets.) Here's the basic outline of comparing sets.

var allnumbersSet = new HashSet<int>(allnumbers);
var allnumbers2Set= new HashSet<int>(allnumbers2);

if (allnumbersSet.IsSupersetOf(allnumbers2Set)) {
   /* everything in allnumbers2 is also in allnumbers1 */
}

The people who put together DotNet did a really good job creating and optimizing those collection classes; you can use them with confidence to get good performance.

edited Mar 27, 2020 at 14:55

answered Mar 27, 2020 at 14:35

O. Jones

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2 Comments

Irdis Over a year ago

I think it's better to leave allnumbers2 as is since it's unnecessary for argument of IsSupersetOf to be HashSet.

Irdis Over a year ago

So basically you want some kind of ienumerable to just walk through and hashset to check if it's there

Pavel Anikhouski · Accepted Answer · 2020-05-05 09:56:18Z

It seems, that you have two-dimensional jagged array. You can simplify your code by using Except and check the difference between allnumbers array and single row at every loop iteration.

static bool CheckLine(int[,][] array)
{
    int[] allnumbers = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
    foreach (var singlearray in array)
    {
        var diff = allnumbers.Except(singlearray);
        if (!diff.Any())
        {
            return true;
        }
    }

    return false;
}

If there is no elements in a difference, it'll mean that single item from source 2D array has all elements from allnumbers array.

Example of the usage

var array = new int[2, 2][];
array[0, 0] = new[] { 1, 2, 8 };
array[0, 1] = new[] { 3, 4, 5, 6 };
array[1, 1] = new[] { 3, 2, 1, 4, 5, 7, 6, 10, 9, 8 };
array[1, 0] = new[] { 1, 2, 3, 4, 5, 6, 7, 8, 9 };

CheckLine(array);

The last two items satisfy the condition, execution will break and return true for { 3, 2, 1, 4, 5, 7, 6, 10, 9, 8 } array. Also don't forget to add using System.Linq directive at the top of file

john · Accepted Answer · 2020-03-27 16:11:40Z

0

Thank you for your help. I forgot to mention that I can use only "using System;"

answered Mar 27, 2020 at 16:11

john

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2 Comments

Pavel Anikhouski Over a year ago

I guess, it should be a comment, not the answer. You can add using System.Linq; and using System.Collections.Generic to make the answers above working

john Over a year ago

I saw its working with using System.Linq; , but Im not allowed to use it. I need to use only "using System;"

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