anagram_Dictionary_Ota_swap.cs

void Main()
{
    Func<string, string, bool> anagram = (first, second) =>
    {
        if (first == null || second == null) return false;
        if (first.Length != second.Length) return false;
        var dic = new Dictionary<char, int>();
        foreach (var item in first)
        {
            int i;
            if (dic.TryGetValue(item, out i))
            {
                dic[item] = i + 1;
            }
            else
            {
                dic[item] = 1;
            }
        }
        //var dic = first.GroupBy(c => c).ToDictionary(kv => kv.Key, kv => kv.Count());
        foreach (var item in second)
        {
            int i;
            if (!dic.TryGetValue(item, out i))
            {
                return false;
            }
            
            i--;

            if (i == 0)
            {
                dic.Remove(item);
            }
            else
            {
                dic[item] = i;
            }
        }
        return true;
    };

    var sw = Stopwatch.StartNew();
    foreach (var item in Enumerable.Range(0, 100000))
    {
        anagram(" ", " ");
        anagram("1", "1");
        anagram("eros", "rose");
        anagram("eros", "lose");
        anagram("", "rose");
        anagram("eros", "rosesssss");
        anagram("bab", "aba");
        anagram(" ", "  ");
        anagram(null, null);
        anagram(null, "");
        anagram("hoge", null);
        anagram("1", "2");
    }
    sw.Stop();
    $"{sw.Elapsed.TotalMilliseconds}ms".Dump("Dictionary");

    Debug.Assert(anagram("", "").Dump());
    Debug.Assert(anagram(" ", " ").Dump());
    Debug.Assert(anagram("1", "1").Dump());
    Debug.Assert(anagram("eros", "rose").Dump());
    Debug.Assert(anagram("eros", "lose").Dump() == false);
    Debug.Assert(anagram("", "rose").Dump() == false);
    Debug.Assert(anagram("eros", "rosesssss").Dump() == false);
    Debug.Assert(anagram("bab", "aba").Dump() == false);
    Debug.Assert(anagram(" ", "  ").Dump() == false);
    Debug.Assert(anagram(null, null).Dump() == false);
    Debug.Assert(anagram(null, "").Dump() == false);
    Debug.Assert(anagram("hoge", null).Dump() == false);
    Debug.Assert(anagram("1", "2").Dump() == false);
    Debug.Assert(anagram("abcde", "abcd").Dump() == false);
}