Kotlin Program to Check Whether a Number can be Expressed as Sum of Two Prime Numbers

To accomplish this task, checkPrime() function is created.

The checkPrime() returns 1 if the number passed to the function is a prime number.

Example: Integer as a Sum of Two Prime Numbers

fun main(args: Array<String>) {
    val number = 34
    var flag = false
    for (i in 2..number / 2) {

        // condition for i to be a prime number
        if (checkPrime(i)) {

            // condition for n-i to be a prime number
            if (checkPrime(number - i)) {

                // n = primeNumber1 + primeNumber2
                System.out.printf("%d = %d + %d\n", number, i, number - i)
                flag = true
            }

        }
    }

    if (!flag)
        println("$number cannot be expressed as the sum of two prime numbers.")
}

// Function to check prime number
fun checkPrime(num: Int): Boolean {
    var isPrime = true

    for (i in 2..num / 2) {
        if (num % i == 0) {
            isPrime = false
            break
        }
    }

    return isPrime
}

When you run the program, the output will be:

34 = 3 + 31
34 = 5 + 29
34 = 11 + 23
34 = 17 + 17

Here's the equivalent Java code: Java Program to Repesent a Number as a sum of two numbers.