Partition for splitting in Kotlin - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Kotlin partition example?

Consider the following Kotlin code that uses the partition function to split a list of integers into even and odd numbers. What will be printed?

Kotlin

val numbers = listOf(1, 2, 3, 4, 5, 6)
val (evens, odds) = numbers.partition { it % 2 == 0 }
println("Evens: $evens")
println("Odds: $odds")

A Evens: [1, 3, 5]\nOdds: [2, 4, 6]

B Evens: [2, 4, 6]\nOdds: [1, 3, 5]

C Evens: [1, 2, 3]\nOdds: [4, 5, 6]

D Evens: []\nOdds: [1, 2, 3, 4, 5, 6]

💡 Hint

Remember, partition splits the list into two lists: one where the condition is true, and one where it is false.

The partition function returns a pair of lists. The first list contains elements where the predicate is true (even numbers), and the second list contains elements where the predicate is false (odd numbers).

❓ Predict Output

intermediate

What is the size of the lists after partition?

Given this Kotlin code, how many elements are in the first and second lists after partitioning by the condition it > 3?

Kotlin

val data = listOf(2, 3, 4, 5, 6)
val (greaterThanThree, notGreaterThanThree) = data.partition { it > 3 }
println("greaterThanThree size: ${greaterThanThree.size}")
println("notGreaterThanThree size: ${notGreaterThanThree.size}")

A greaterThanThree size: 3\nnotGreaterThanThree size: 2

B greaterThanThree size: 0\nnotGreaterThanThree size: 5

C greaterThanThree size: 5\nnotGreaterThanThree size: 0

D greaterThanThree size: 2\nnotGreaterThanThree size: 3

💡 Hint

Count how many numbers in the list are greater than 3.

Numbers greater than 3 are 4, 5, and 6 (3 elements). The rest (2 and 3) are not greater than 3 (2 elements).

❓ Predict Output

advanced

What is the output when partitioning a list of strings by length?

Look at this Kotlin code that partitions a list of strings by whether their length is greater than 3. What will be printed?

Kotlin

val words = listOf("cat", "house", "dog", "elephant")
val (longWords, shortWords) = words.partition { it.length > 3 }
println("Long words: $longWords")
println("Short words: $shortWords")

A Long words: []\nShort words: [cat, house, dog, elephant]

B Long words: [cat, dog]\nShort words: [house, elephant]

C Long words: [cat, house, dog]\nShort words: [elephant]

D Long words: [house, elephant]\nShort words: [cat, dog]

💡 Hint

Check the length of each word carefully.

Words with length greater than 3 are "house" (5) and "elephant" (8). The others have length 3 or less.

❓ Predict Output

advanced

What error occurs when using partition incorrectly?

What error will this Kotlin code produce?

Kotlin

val numbers = listOf(1, 2, 3)
val (evens, odds) = numbers.partition { it % 2 == 0 }
println(evens[3])

A NoSuchElementException

B NullPointerException

C IndexOutOfBoundsException

D ClassCastException

💡 Hint

Check the size of the evens list and the index accessed.

The evens list contains [2]. Accessing index 3 is out of bounds, causing IndexOutOfBoundsException.

🧠 Conceptual

expert

Which option correctly describes the behavior of Kotlin's partition function?

Choose the statement that best describes what Kotlin's partition function does when called on a collection.

A It splits the collection into two lists: the first contains elements matching the predicate, the second contains elements not matching it.

B It filters the collection and returns a single list with elements matching the predicate.

C It removes all elements that match the predicate from the original collection.

D It sorts the collection into ascending and descending order lists.

💡 Hint

Think about how partition divides elements based on a condition.

Partition returns a pair of lists: one with elements where the predicate is true, and one where it is false.