Parsing and Multiplying Numbers in Kotlin | CodeSignal Learn

Parsing and Multiplying Numbers in Kotlin | CodeSignal Learn

Introduction

Welcome! In this unit, we have an exciting and practical task that will test your Kotlin programming skills . We will be parsing strings and making type conversions. So, let's dive into it!

Task Statement and Description

Our task for the day involves creating a Kotlin function called parseAndMultiplyNumbers() . This function is designed to accept a string as an input. However, it's not just any string — the input we'll consider is a playful mix of numbers and words. The purpose of this function is to analyze the input string, extract all the numbers, convert these numbers (currently string types) into integer data types, and then multiply all these numbers together. The final output? It's the product of all those numbers! Here's an illustration for clarification. Given the input string "I have 2 apples and 5 oranges," our function should return the product of 2 and 5, which is 10.

Step-by-Step Solution Building: Step 1

The primary task is to parse the string and identify the numbers. To do that, let's create an empty string, num, to accumulate digits and a MutableList<Int> to collect all the numbers we find: Kotlin val inputString = "I have 2 apples and 5 oranges" var num = "" val numbers = mutableListOf<Int>()

Step-by-Step Solution Building: Step 2

The next step requires iterating through the input string character by character. When we encounter a digit, we append it to our num string. If a character isn’t a digit and num isn’t empty, it means we've reached the end of a number. At this point, we convert num to an integer, add it to the numbers list, and reset num to an empty string. If the character isn’t a digit and num is empty, we simply skip and progress. Kotlin for (ch in inputString) {if (ch.isDigit()) {num += ch} else if (num.isNotEmpty()) {numbers.add(num.toInt()) num = ""}} // After the loop, we must check if 'num' is not empty // because it indicates that the last part of the string contains a number. if (num.isNotEmpty()) {numbers.add(num.toInt())} for (number in numbers) {print("$number ")} After running this code, the output should be 2 5 .

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Step-by-Step Solution Building: Step 3

Finally, we multiply all the numbers in the numbers list together. The multiplication result gets stored in the result variable. var result = 1 for (number in numbers) {result *= number} println(result) After executing this code, the console output should be 10 .

Full Solution

Bringing together all the steps, our final Kotlin solution manifests as follows: fun parseAndMultiplyNumbers(inputString: String): Int {var num = "" val numbers = mutableListOf<Int>() for (ch in inputString) {if (ch.isDigit()) {num += ch} else if (num.isNotEmpty()) {numbers.add(num.toInt()) num = ""}} if (num.isNotEmpty()) {numbers.add(num.toInt())} var result = 1 for (number in numbers) {result *= number} return result} fun main() {// Call the function println(parseAndMultiplyNumbers("I have 2 apples and 5 oranges"))} This solution also caters to numbers situated at the end of the input string.

Kotlin

fun parseAndMultiplyNumbers(inputString: String): Int {
    var num = ""
    val numbers = mutableListOf<Int>()

    for (ch in inputString) {
        if (ch.isDigit()) {
            num += ch
        } else if (num.isNotEmpty()) {
            numbers.add(num.toInt())
            num = ""
        }
    }
    if (num.isNotEmpty()) {
        numbers.add(num.toInt())
    }

    var result = 1
    for (number in numbers) {
        result *= number
    }
    return result
}

fun main() {
    // Call the function
    println(parseAndMultiplyNumbers("I have 2 apples and 5 oranges"))
}