public static int sherlockAndAnagrams(string s)
    {
        int pairsCount = 0;
        Dictionary<string, List<string>> subs = 
            new Dictionary<string, List<string>>();
        
        for (int l = 1; l <= s.Length; l++) {
            for (int i = 0; i <= s.Length - l; i++) {
                string subStr = s.Substring(i, l);
                string hc = GetHashCode(subStr);
                if (!subs.ContainsKey(hc))
                    subs.Add(hc, new List<string>());
                subs[hc].Add(subStr);                
            }
        }
        
        foreach (var kv in subs) {
            if (kv.Value.Count() > 1)
                pairsCount += (kv.Value.Count() * (kv.Value.Count()-1))/2;
        }
        
        return pairsCount;
    }
    
    private static string GetHashCode(string subStr) {
        int[] chars = new int[26];
        foreach (char ch in subStr) {
            chars[(int)(ch - 'a')]++;
        }
        var strCodes = chars.Select(c => c.ToString());
        return string.Join("", strCodes);
    }