345. 反转字符串中的元音字母

题目链接：https://leetcode-cn.com/problems/reverse-vowels-of-a-string/
执行用时：68 ms, 在所有 Swift 提交中击败了92.31% 的用户
内存消耗：15.9 MB, 在所有 Swift 提交中击败了38.46% 的用户

class Solution {
    func reverseVowels(_ s: String) -> String {
        var chars = Array(s)
        var left = 0, right = chars.count-1
        var flag = false
        let vowels: Set<Character> = ["A", "E", "I", "O", "U", "a", "e", "i", "o", "u"]
        while left < right {
            //左边遇到元音字符
            flag = vowels.contains(chars[left])
            if flag && vowels.contains(chars[right]) {
                chars.swapAt(left, right)
                left += 1
                right -= 1
            }else if flag {
                right -= 1
            }else {
                left += 1
            }
        }
        let str = String(chars)
        return str
    }
}

使用switch case 匹配的写法

class Solution {
    func reverseVowels(_ s: String) -> String {
        var chars = Array(s)
        var left = 0, right = chars.count-1
        var tmp:Character
        var flag1 = false, flag2 = false
        while left < right {
            switch chars[left] {
            case "a", "e", "i", "o", "u","A","E","I","O","U":
                flag1 = true
            default:
                left += 1
                flag1 = false
                break
            }
            switch chars[right] {
            case "a", "e", "i", "o", "u","A","E","I","O","U":
                flag2 = true
            default:
                right -= 1
                flag2 = false
                break
            }
            if flag1 && flag2 {
                chars.swapAt(left, right)
                left += 1
                right -= 1
            }
        }
        let str = String(chars)
        return str
    }
}