CareerCup

public class Program
    {
        public static void Main(string[] args)
        {
            var dict = new Dictionary<string, int>();
            dict.Add("a", 1);
            dict.Add("aa", 1);
            dict.Add("aaa", 1);
            
            var input = "aaabaa";
            
            get_combinations(input, dict);
            
        }
        
        public static void get_combinations(string input, Dictionary<string, int> dict)
        {
            for (int i = 0; i < input.Length; i++)
            {
                for (int j = i ; j < input.Length ; j++)
                {
                    if (dict.ContainsKey(input.Substring(i, j-i+1)))
                    {
                        Console.WriteLine(input.Substring(i, j-i+1));
                    }
                }
            }
        }
    }

Find all substrings, find them in dictionary, if found, add to return list.

public void findSubStringInDictionary() {
		String s = "abcdefabcd";
		Set<String> d = new HashSet<String> (Arrays.asList("a", "cdf", "bcd", "ef"));
		System.out.println(findSubString(s,d));
	}

	public List<String> findSubString(String s, Set<String> dictionary) {
		List<String> retSet = new LinkedList<String>();
		for (int ii = 0; ii < s.length(); ii++) {
			for (int jj = ii; jj <= s.length(); jj++) {
				if (dictionary.contains(s.substring(ii,  jj))) {
					retSet.add(s.substring(ii,  jj));
				}
			}
		}
		return retSet;
	}