private int CountValidPasswordsRuleTwo()
{
int validPasswordCount = 0;
foreach (var passwordAndRule in InputLines)
{
if (!Regex.IsMatch(passwordAndRule, DayTwoConstants.FormatRegex))
{
continue;
}
var passPieces = passwordAndRule.Split(": ");
var rule = new PasswordRuleTwo(passPieces[0]);
var password = passPieces[1];
if (!rule.IsValid())
{
continue;
}
if (PasswordIsValidRuleTwo(password, rule))
{
validPasswordCount++;
}
}
return(validPasswordCount);
}
private bool PasswordIsValidRuleTwo(string password, PasswordRuleTwo rule)
{
if (password.Length < rule.SecondPosition)
{
return(false);
}
return(password[rule.FirstPosition - 1].Equals(rule.Letter) ^ password[rule.SecondPosition - 1].Equals(rule.Letter));
}