Letter Combinations of a Phone Number - Kotlin

gistfile1.txt

class Solution {
    private val vals = arrayOf("", "", "abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz")
private var result: MutableList<String> = mutableListOf()

fun letterCombinations(digits: String): List<String> {
    if (digits.isEmpty()) return result

    dfs(digits, 0, "")
    return result
}

private fun dfs(digits: String, cur: Int, temp: String) {
    if (cur == digits.length) {
        result.add(temp)
        return
    }

    val num = digits[cur].toInt() - '0'.toInt()
    for (c in vals[num]) {
        dfs(digits, cur + 1, temp + c)
    }
}
}