Removing strings with duplicate letters from string array

Question

I have array of strings like

string[] A = { "abc", "cccc", "fgaeg", "def" };

I would like to obtain a list or array of strings where any letter appears only one time. I means that "cccc", "fgaeg" will be removed from input array. I managed to do this but I feel that my way is very messy, unnecessarily complicated and not efficient.

Do you have any ideas to improve this algorythm (possibliy replacing with only one Linq query)?

My code:

        var goodStrings = new List<string>();
        int i = 0;
        foreach (var str in A)
        {
            var tempArr = str.GroupBy(x => x)
                .Select(x => new
                {
                    Cnt = x.Count(),
                    Str = x.Key
                }).ToArray();

            var resultArr = tempArr.Where(g => g.Cnt > 1).Select(f => f.Str).ToArray();
            if(resultArr.Length==0) goodStrings.Add(A[i]);
            
            i++;
        }

I think, the check could be done with Regex, something like ".*(\w).*\1.*" — Turo
– Turo, Commented Jun 25, 2020 at 13:04

Pavel Anikhouski · Accepted Answer · 2020-06-25 13:06:43Z

4

You can use Distinct method for every array item and get items with count of distinct items equals to original string length

string[] A = { "abc", "cccc", "fgaeg", "def" };
var result = A.Where(a => a.Distinct().Count() == a.Length).ToList();

You'll get list with abc and def values, as expected

edited Jun 25, 2020 at 13:06

answered Jun 25, 2020 at 12:59

Pavel Anikhouski

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3 Comments

Rafael Over a year ago

Very nice approach. It didn't cross my mind. Simple and clean.

Franck Over a year ago

Also if strings can be long enough it might be worth it to get rid of all string with more than 26 character right of the bat.

Pavel Anikhouski Over a year ago

@Franck Thank you, that's the good point. However, OP didn't mentioned such requirements, like string length or used alphabet

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