public IEnumerable <string> FindPalindromes(string input)
{
if (string.IsNullOrWhiteSpace(input))
{
throw new ArgumentException("input string cannot be null or empty");
}
//STEP 1. A palindrome will start and end with the same character.
//we'll start by geting all the (unique) substrings that start and end with the same character.
HashSet <string> substrings = new HashSet <string>(StringComparer.InvariantCultureIgnoreCase);
for (int i = 0; i < input.Length; i++)
{
var startAndEndChar = input[i];
var results = substringer.FindSubstrings(input.Substring(i), input[i]);
if (results == null)
{
break;
}
foreach (var result in results)
{
substrings.Add(result);
}
}
//STEP 2. All previously obtained substrings will be validated to see if they meet Palindrome criterion
// If they do, they will be added to the Palindrome HashSet which will ensure uniqueness.
foreach (var substring in substrings)
{
if (validator.IsValidPalindrome(substring))
{
palindromeCollection.Add(substring);
}
}
return(palindromeCollection);
}