CODEWITHSUNDEEP
kotlin
memeprincess
memeprincess

Reputation: 338

How to check if a String can be made out of specified list of Chars?

I've been trying to create a method that will return true if chars can be used to create a word. For example, listOf('a', 'b', 'o'), "baobab") -> true, and it works fine, but with input: listOf('a, 'a', "aa") it returns false instead of true. Can you please tell me what's wrong?

fun canBuildFrom(chars: List<Char>, word: String): Boolean {
    var i = 0
    for (item in chars) {
        for (char in word) {
            if (char.toLowerCase() == item.toLowerCase()) {
                i++
            }
        }
    }
    return (i == word.length)
}

Upvotes: 1

Views: 402

Answers (1)

Deadbeef
Deadbeef

Reputation: 1681

Here's a simple approach:

fun canBuildFrom(chars: List<Char>, word: String) = word.all { char -> char in chars}

If you want it to be case insensitive:

fun canBuildFrom(chars: List<Char>, word: String) = chars.map(Char::toLowerCase).let { lowerCasedChars ->
    word.all { char ->
        char.toLowerCase() in lowerCasedChars
    }
}

The function can be improved by making it an extension of String, and accepting broader interfaces that has contains. i.e. String.canBuildFrom(chars:Collection<Char>)

Why your code didn't work: Your function accepts a list of Chars as an input. For every characters in the string, i is increased by the number of times the character appears in the list.

Here's some inputs that it might get wrong:

listOf('a', 'a', 'a'), "abb" -> true // should be false
listOf('a', 'b', 'c', 'c'), "abcbcbacbc" -> false // should be true

Upvotes: 2

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