Find character with most occurrences in string?

Question

For example, I have a string:

\"abbbbccd\"

b has the most occurrences. When using C++, the easiest way to handle this is inser

Answer 1

This is Femaref's solution modified to return multiple letters if their Count matches. Its no longer a one-liner but still reasonably concise and should be fairly performant.

    public static IEnumerable GetMostFrequentCharacters(this string str)
    {
        if (string.IsNullOrEmpty(str))
            return Enumerable.Empty();

        var groups = str.GroupBy(x => x).Select(x => new { Letter = x.Key, Count = x.Count() }).ToList();
        var max = groups.Max(g2 => g2.Count);
        return groups.Where(g => g.Count == max).Select(g => g.Letter);
    }