AdventDay2.swift

func isvalidPasswordPolicy(_ password: String) -> Bool {
    // Output
    var isValidPasswordPolicy = false
    
    // Get the component of each password policy
    let components = password.components(separatedBy: CharacterSet.whitespaces)

    // From 1st component  get the lower and upper bound
    let first = components[0].components(separatedBy: "-")
    guard let lowerBound = Int(first.first ?? "0") else { return isValidPasswordPolicy }
    guard let upperBound = Int(first.last ?? "0") else { return isValidPasswordPolicy }
    
    // From 2nd component get the character upon which policy can be applied
    let second = components[1].first
    // From 3rd Component get the entire string
    let third = components[2]
    
    // Store the character count
    var countOfChar = 0
    
    // Check if there is match
    for eachChar in third {
        if eachChar == second {
            countOfChar += 1
        }
    }
    
    // check if count lies in between or including lower or upper bound 
    if countOfChar >= lowerBound && countOfChar <= upperBound {
        isValidPasswordPolicy = true
    }
    
    // return it
    return isValidPasswordPolicy
}