public static bool IsValid(string input)
{
var(digit1, digit2, letter, password) = PolicyValidator.Parse(input);
var count = password.Count(x => x == letter);
var isValid = count >= digit1 && count <= digit2;
return(isValid);
}
public static bool IsValid2(string input)
{
var(digit1, digit2, letter, password) = PolicyValidator.Parse(input);
var isPos1 = password[digit1 - 1] == letter;
var isPos2 = password[digit2 - 1] == letter;
var isValid = isPos1 ^ isPos2;
return(isValid);
}