如何比较两个字符串以检查一个是否包含另一个，而不考虑字符的顺序

Question

I have two strings, and I need to know if one is contained in the other, completely ignoring the order of the characters of both of them.

Example:

            string container = "WWGAAFWW";
            string element = "WA";
            Debug.Log(container.Contains(element));

This gives false, but I need it to be true, because W and A are contained in the container string. I know there is a method to sort lists, but even then, container would become AAFGWWWW and comparing them would still give false. Both string could be longer than this example (but not by much, i think). After having checked that, if the second string is contained (the way I intend) I would also need to remove it from the first one, so in the example, I want the end result to be WGAFWWF. I can't think of a simple way to do this, and I couldn't find any example on how to. Any idea?

Answer 1

I am not sure whether it is what you want

After this function, container will remove the element

    static bool CCstring(ref string container, string element)
    {
        string temp = container;
        foreach (char c in element)
        {
            if (!container.Contains(c.ToString()))
            {
                container = temp;
                return false;
            }
            else
            {
                container = container.Remove(container.IndexOf(c), 1);
            }
        }
        return true;
    }

Answer 2

you could check this easily using a loop. It's a simple way of doing time complexity O(M*N), because it's checking each char of one string into another string.

private static bool Contains(string container, string element)
{
    foreach (char ch in element)
    {
        if (container.Contains(ch) == false)
        {
            return false;
        }
    }

    return true;
}

Answer 3

The following approach uses a dictionary to track character counts in the container and ensures a corresponding amount are deducted for each character in element.

private static IDictionary<char, int> ExtractDictionaryFromString(string value)
{
    var result = new Dictionary<char, int>();
    foreach (var c in value.ToCharArray())
    {
        if (!result.TryGetValue(c, out int count))
        {
            result.Add(c, 0);
        }

        result[c] = result[c] + 1;
    }

    return result;
}

private static bool IsElementInContainer(ref string container, string element)
{
    var lookup = ExtractDictionaryFromString(container);
    foreach (var c in element.ToCharArray())
    {
        if (!lookup.TryGetValue(c, out int count) || count == 0)
        {
            return false;
        }

        lookup[c] = lookup[c] - 1;
    }

    StringBuilder sb = new StringBuilder();
    foreach (var c in lookup)
    {
        for (int i = 0; i < c.Value; i++)
        {
            sb.Append(c.Key);
        }
    }

    container = sb.ToString();
    return true;
}

This does not require continuous re-parsing of container, which depending on the length of these strings could be expensive.

Usage:

    string container = "WWGAAFWW";
    string  element = "WA";
    Console.WriteLine(IsElementInContainer(ref container, element));
    Console.WriteLine(container);

Note that the returned version of container is not in a predefined sequence. If that is important to you, another solution would be more appropriate.

A variant of this approach, left to the reader, would be to replace the Dictionary with an ImmutableDictionary equivalent. This would allow you to create the Dictionary object once and pass it to IsElementInContainer instead of regenerating it on each call.

Answer 4

Using LINQ, you could declare the following

bool containsAll = container.Except(element.ToCharArray()).Any();