findArmstrongNumbersRange()

Step 1: Understand the Problem

A Armstrong number is a number that is the sum of its own digits each raised to the power of the number of digits. For example, 153 is an Armstrong number since 1^3 + 5^3 + 3^3 = 153. Our task is to implement a function that finds all Armstrong numbers within a given range.

func isArmstrongNumber(_ num: Int) -> Bool {
   // function implementation to be done in the steps below
}

func findArmstrongNumbersInRange(_ start: Int, _ end: Int) -> [Int] {
   // function implementation to be done in the steps below
}

Step 2: Implement the isArmstrongNumber Function

To check if a number is an Armstrong number, we first convert the number to a string to easily get the number of digits. Then, we iterate over the digits and sum the power of each digit to the count of digits. If the sum is equal to the original number, then it's an Armstrong number.

func isArmstrongNumber(_ num: Int) -> Bool {
    let strNum = String(num)
    let count = strNum.count
    var sum = 0

    for char in strNum {
        if let digit = Int(String(char)) {
            sum += pow(Double(digit), Double(count))
        }
    }

    return sum == num
}

Step 3: Implement the findArmstrongNumbersInRange Function

In this function, we iterate over the range and call the isArmstrongNumber function for each number. If the function returns true, we add the number to the result array.

func findArmstrongNumbersInRange(_ start: Int, _ end: Int) -> [Int] {
    var result = [Int]()

    for num in start...end {
        if isArmstrongNumber(num) {
            result.append(num)
        }
    }

    return result
}

Step 4: Test the Function

Let's test the function with the range 1 to 500.

let armstrongNumbers = findArmstrongNumbersInRange(1, 500)
print(armstrongNumbers)  // prints: [1, 2, 3, 4, 5, 6, 7, 8, 9, 153, 370, 371, 407]

Conclusion

By breaking down the problem into smaller tasks, we managed to implement a function to find all Armstrong numbers within a given range. It involves understanding the characteristics of Armstrong numbers, implementing a helper function to check if a number is an Armstrong number, and then implementing the main function to find Armstrong numbers in the range.