Exercise: Range Operations
Implement the following functions using range operations:
calculateSumOfSquaresfunction that takes an integernas an argument and returns the sum of the squares of all positive integers from 0 ton.calculateSumOfEvenfunction that takes an integernas an argument and returns the sum of all even numbers from 0 ton.countDownByStepfunction that takes three integers:start,end, andstep, and returns a string representation of the numbers fromstartdown toend, with each step beingstepunits apart.
fun calculateSumOfSquares(n: Int): Int = TODO()
fun calculateSumOfEven(n: Int): Int = TODO()
fun countDownByStep(
start: Int,
end: Int,
step: Int
): String = TODO()
Example usage:
// Examples for calculateSumOfSquares
println(calculateSumOfSquares(0)) // 0
println(calculateSumOfSquares(1)) // 1
println(calculateSumOfSquares(2)) // 5 (1 + 4)
println(calculateSumOfSquares(3)) // 14 (1 + 4 + 9)
println(calculateSumOfSquares(4)) // 30 (1 + 4 + 9 + 16)
// Example for calculateSumOfEven
println(calculateSumOfEven(0)) // 0
println(calculateSumOfEven(1)) // 0
println(calculateSumOfEven(2)) // 2
println(calculateSumOfEven(3)) // 2
println(calculateSumOfEven(5)) // 6 (2 + 4)
println(calculateSumOfEven(10))
// 30 (2 + 4 + 6 + 8 + 10)
println(calculateSumOfEven(12))
// 42 (2 + 4 + 6 + 8 + 10 + 12)
println(calculateSumOfEven(20))
// 110 (2 + 4 + 6 + 8 + 10 + 12 + 14 + 16 + 18 + 20)
// Example for countDownByStep
println(countDownByStep(1, 1, 1)) // 1
println(countDownByStep(5, 1, 2)) // 5, 3, 1
println(countDownByStep(10, 1, 3)) // 10, 7, 4, 1
println(countDownByStep(15, 5, 5)) // 15, 10, 5
println(countDownByStep(20, 2, 3))
// 20, 17, 14, 11, 8, 5, 2
println(countDownByStep(10, 4, 3)) // 10, 7, 4
println(countDownByStep(-1, -1, 1)) // -1
println(countDownByStep(-5, -9, 2)) // -5, -7, -9
This problem can either be solved in the below playground or you can clone kotlin-exercises project and solve it locally. In the project, you can find code template for this exercise in essentials/loops/Loops.kt. You can find there starting code, example usage and unit tests.
Once you are done with the exercise, you can check your solution here.
Playground
import org.junit.Test
import kotlin.test.assertEquals
fun calculateSumOfSquares(n: Int): Int = TODO()
fun calculateSumOfEven(n: Int): Int = TODO()
fun countDownByStep(
start: Int,
end: Int,
step: Int
): String = TODO()
fun main() {
// Examples for calculateSumOfSquares
println(calculateSumOfSquares(0)) // 0
println(calculateSumOfSquares(1)) // 1
println(calculateSumOfSquares(2)) // 5 (1 + 4)
println(calculateSumOfSquares(3)) // 14 (1 + 4 + 9)
println(calculateSumOfSquares(4)) // 30 (1 + 4 + 9 + 16)
// Example for calculateSumOfEven
println(calculateSumOfEven(0)) // 0
println(calculateSumOfEven(1)) // 0
println(calculateSumOfEven(2)) // 2
println(calculateSumOfEven(3)) // 2
println(calculateSumOfEven(5)) // 6 (2 + 4)
println(calculateSumOfEven(10))
// 30 (2 + 4 + 6 + 8 + 10)
println(calculateSumOfEven(12))
// 42 (2 + 4 + 6 + 8 + 10 + 12)
println(calculateSumOfEven(20))
// 110 (2 + 4 + 6 + 8 + 10 + 12 + 14 + 16 + 18 + 20)
// Example for countDownByStep
println(countDownByStep(1, 1, 1)) // 1
println(countDownByStep(5, 1, 2)) // 5, 3, 1
println(countDownByStep(10, 1, 3)) // 10, 7, 4, 1
println(countDownByStep(15, 5, 5)) // 15, 10, 5
println(countDownByStep(20, 2, 3))
// 20, 17, 14, 11, 8, 5, 2
println(countDownByStep(10, 4, 3)) // 10, 7, 4
println(countDownByStep(-1, -1, 1)) // -1
println(countDownByStep(-5, -9, 2)) // -5, -7, -9
}
class LoopsTest {
@Test
fun testCalculateSumOfSquares() {
assertEquals(1, calculateSumOfSquares(1))
assertEquals(5, calculateSumOfSquares(2))
assertEquals(14, calculateSumOfSquares(3))
assertEquals(30, calculateSumOfSquares(4))
assertEquals(385, calculateSumOfSquares(10))
assertEquals(0, calculateSumOfSquares(0))
assertEquals(0, calculateSumOfSquares(-1))
assertEquals(0, calculateSumOfSquares(-1))
assertEquals(0, calculateSumOfSquares(-3))
}
@Test
fun testCalculateSumOfEven() {
assertEquals(0, calculateSumOfEven(0))
assertEquals(0, calculateSumOfEven(1))
assertEquals(2, calculateSumOfEven(2))
assertEquals(2, calculateSumOfEven(3))
assertEquals(6, calculateSumOfEven(5))
assertEquals(30, calculateSumOfEven(10))
assertEquals(42, calculateSumOfEven(12))
assertEquals(110, calculateSumOfEven(20))
assertEquals(240, calculateSumOfEven(30))
assertEquals(0, calculateSumOfEven(-1))
}
@Test
fun testCountDownByStep() {
assertEquals("1", countDownByStep(1, 1, 1))
assertEquals("5, 3, 1", countDownByStep(5, 1, 2))
assertEquals("10, 7, 4, 1", countDownByStep(10, 1, 3))
assertEquals("15, 10, 5", countDownByStep(15, 5, 5))
assertEquals("20, 17, 14, 11, 8, 5, 2", countDownByStep(20, 2, 3))
assertEquals("10, 7, 4", countDownByStep(10, 4, 3))
assertEquals("-1", countDownByStep(-1, -1, 1))
assertEquals("-5, -7, -9", countDownByStep(-5, -9, 2))
assertEquals("0", countDownByStep(0, 0, 1))
assertEquals("0", countDownByStep(0, 0, 2))
}
}
