Leetcode 49 - group anagrams - study code

Leetcode49_groupAnagrams_StudyCode.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Leetcode49_groupAnagrams
{
    /// <summary>
    /// Leetcode 49 
    /// study code submission in the discussion 
    /// https://discuss.leetcode.com/topic/24494/share-my-short-java-solution
    /// </summary>
    class Program
    {
        static void Main(string[] args)
        {
        }

        public List<List<String>> groupAnagrams(String[] strs) {
	        if(strs == null || strs.Length == 0){
		        return new List<List<String>>();
	        }

	        var map = new Dictionary<String, List<String>>();
	        
	        foreach (String s in strs) {
		        char[] ca = s.ToCharArray();
		        Array.Sort(ca);

		        String keyStr = new string(ca);
		        if(!map.ContainsKey(keyStr))
                {
			        map.Add(keyStr, new List<String>());
                }

		        map[keyStr].Add(s);
	        }	       

	        return new List<List<String>>(map.Values);
        }
    }
}