Question

How to count the occurrences of each letter in char array with Kotlin

Answer 1

fun countLetterOccurrencesFold(charArray: CharArray): Map<Char, Int> {
    return charArray.fold(mutableMapOf()) { acc, char ->
        acc.apply { this[char] = getOrDefault(char, 0) + 1 }
    }
}

fun main() {
    val charArray = charArrayOf('k', 'o', 'k', 'c', 'd', 'c', 'e', 'f', 'e', 'k')
    
    val occurrences = countLetterOccurrencesFold(charArray)
    
    println(occurrences)
    
    println(occurrences.map { "${it.key}: ${it.value}" }.joinToString(", \n"))
}
 
 
    
/*
run:
 
{k=3, o=1, c=2, d=1, e=2, f=1}
k: 3, 
o: 1, 
c: 2, 
d: 1, 
e: 2, 
f: 1
  
*/

 

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