LeetCode in Kotlin

345. Reverse Vowels of a String

Easy

Given a string s, reverse only all the vowels in the string and return it.

The vowels are 'a', 'e', 'i', 'o', and 'u', and they can appear in both lower and upper cases, more than once.

Example 1:

Input: s = “hello”

Output: “holle”

Example 2:

Input: s = “leetcode”

Output: “leotcede”

Constraints:

• 1 <= s.length <= 3 * 105
• s consist of printable ASCII characters.

Solution

class Solution {
    private fun isVowel(c: Char): Boolean {
        return c == 'a' || c == 'A' || c == 'e' || c == 'E' || c == 'i' || c == 'I' || c == 'o' || c == 'O' ||
            c == 'u' || c == 'U'
    }

    fun reverseVowels(str: String): String {
        var i = 0
        var j = str.length - 1
        val str1 = str.toCharArray()
        while (i < j) {
            if (!isVowel(str1[i])) {
                i++
            } else if (!isVowel(str1[j])) {
                j--
            } else {
                // swapping
                val t = str1[i]
                str1[i] = str1[j]
                str1[j] = t
                i++
                j--
            }
        }
        return String(str1)
    }
}

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