Simple c# charcount solution 97% runtime, 100% memory
```\npublic string SortString(string s) {\n        int[] counters = new int[26];\n        var sb = new StringBuilder();\n\t\t\n        foreach (var cur in s) {\
```\npublic string SortString(string s) {\n        int[] counters = new int[26];\n        var sb = new StringBuilder();\n\t\t\n        foreach (var cur in s) {\n            counters[cur - \'a\'] ++;\n        }\n\t\t\n        while (sb.Length < s.Length) {         \n            for (int i = 0; i < counters.Length; i++) {\n                if (counters[i] > 0) {\n                    sb.Append((char)(\'a\' + i));\n                    counters[i]--;\n                }\n            }\n            for (int i = counters.Length - 1; i >= 0; i--) {\n                if (counters[i] > 0) {\n                    sb.Append((char)(\'a\' + i));\n                    counters[i]--;\n                }\n            }\n        }\n        \n        return sb.ToString();\n    }
['Counting Sort', 'C#']