GroupBy for categorization in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to group the list of words by their first letter.

Kotlin

val words = listOf("apple", "banana", "apricot", "blueberry")
val grouped = words.groupBy { it.[1] }
println(grouped)

Drag options to blanks, or click blank then click option'

Afirst()

Blength

Clast()

Duppercase()

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'length' instead of 'first()' groups by word length, not first letter.

Using 'last()' groups by last letter, not first.

The groupBy function groups elements by the key returned by the lambda. Using it.first() groups words by their first letter.

2fill in blank

medium

Complete the code to group numbers by their remainder when divided by 3.

Kotlin

val numbers = listOf(1, 2, 3, 4, 5, 6)
val grouped = numbers.groupBy { it [1] 3 }
println(grouped)

Drag options to blanks, or click blank then click option'

A%

B*

C/

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using '*' or '+' changes the number, not the remainder.

Using '/' gives the quotient, not remainder.

The '%' operator gives the remainder. Grouping by 'it % 3' groups numbers by their remainder when divided by 3.

3fill in blank

hard

Fix the error in the code to group words by their length.

Kotlin

val words = listOf("cat", "dog", "bird")
val grouped = words.groupBy { it.[1] }
println(grouped)

Drag options to blanks, or click blank then click option'

Asize

Bcount

Clength

Dlength()

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'size' causes errors; that's for collections like lists, strings use 'length'.

Using 'length()' or 'count'; 'length' is a property (no ()), 'count()' is a function but not standard for length.

In Kotlin, the property 'length' gives the length of a string. 'size' is for collections, 'length()' is incorrect (property, no ()), 'count' is a function.

4fill in blank

hard

Fill both blanks to group words by their last character and filter groups with more than one word.

Kotlin

val words = listOf("apple", "angle", "banana", "bottle", "cat")
val grouped = words.groupBy { it.[1] }.filter { it.value.size [2] 1 }
println(grouped)

Drag options to blanks, or click blank then click option'

Alast()

B>

C==

Dfirst()

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'first()' groups by first letter, not last.

Using '==' 1 filters groups with exactly one word, not more.

Using 'last()' groups words by their last letter. Filtering with '>' 1 keeps groups with more than one word.

5fill in blank

hard

Fill all three blanks to create a map of words grouped by the lowercase version of their first letter, including only groups with more than two words.

Kotlin

val words = listOf("apple", "apricot", "banana", "blueberry", "avocado", "blackberry")
val grouped = words.groupBy { it.[1].toString().[2]() }.filter { it.value.size [3] 2 }
println(grouped)

Drag options to blanks, or click blank then click option'

Afirst()

Bsize

C>

Dlowercase

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'size' as a function instead of property.

Using '>' incorrectly in filter condition.

Using 'toString()' unnecessarily or missing it.

Use 'first()' to get the first letter, then 'lowercase()' to convert it to lowercase. Filter groups with size greater than 2.