AdventDay2Part2.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 var lowerBound = Int(first.first ?? "0") else { return isValidPasswordPolicy }
    // Since we need to match the index
    lowerBound -= 1
    guard var upperBound = Int(first.last ?? "0") else { return isValidPasswordPolicy }
   // Since we need to match the index
    upperBound -= 1
    
    // 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 numberOfmatch count
    var numberOfmatch = 0
    
    // Check if there is match
    for (eachIndex, eachChar) in third.enumerated() {
        if (eachIndex == lowerBound && eachChar == second) || (eachIndex == upperBound && eachChar == second) {
            numberOfmatch += 1
        }
    }
    
    // check if count lies in between
    if numberOfmatch == 1 {
        isValidPasswordPolicy = true
    }
    
    // return it
    return isValidPasswordPolicy
}