Anonymous Kotlin function: Sum of odd numbers in a list

Last update on February 04 2025 11:06:39 (UTC/GMT +8 hours)

Write an anonymous Kotlin function to calculate the sum of all odd numbers in a list.

Pre-Knowledge (Before You Start!)

Before solving this exercise, you should be familiar with the following concepts:

• Lists: A list in Kotlin is an ordered collection of elements. Here, we are working with a list of integers.
• Anonymous Functions: Anonymous functions in Kotlin allow us to define functions without explicitly naming them. These functions can be assigned to variables.
• Loops: Understanding how to iterate over a list using a for loop is essential to process each element.
• Modulo Operator (%): The modulo operator is used to determine whether a number is even or odd. If number % 2 != 0, the number is odd.
• Conditional Statements: You need to use an if condition to check if a number is odd before adding it to the sum.

Hints (Try Before Looking at the Solution!)

Here are some hints to help you solve the problem:

• Hint 1: Define an anonymous function that takes a list of integers as a parameter and returns an integer.
• Hint 2: Initialize a variable to store the sum of odd numbers, starting at 0.
• Hint 3: Iterate through the list using a for loop.
• Hint 4: Check if a number is odd using number % 2 != 0. If true, add it to the sum.
• Hint 5: Return the final sum after iterating through all numbers in the list.

Sample Solution:

Kotlin Code:

fun main() {
    val numbers = listOf(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)

    val sumOfOdds: (List<Int>) -> Int = fun(list: List<Int>): Int {
        var sum = 0
        for (number in list) {
            if (number % 2 != 0) {
                sum += number
            }
        }
        return sum
    }

    val oddSum = sumOfOdds(numbers)
    println("Original list of elements: $numbers")
    println("Sum of odd numbers: $oddSum")
}

Sample Output:

Original list of elements: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]
Sum of odd numbers: 36

Explanation:

In the above exercise -

• We define an anonymous function called sumOfOdds with the type (List<Int>) -> Int. It takes a list of integers as its parameter and returns the sum of all odd numbers in the list as an integer.
• Inside the sumOfOdds function, we initialize a variable sum to keep track of the sum, initially set to 0.
• We iterate through each number in the input list using a for loop. If a number is odd (i.e., not divisible by 2), we add it to the sum variable.
• In the end, we return the sum of all odd numbers in the list, which represents the final value of sum.

Kotlin Editor:

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