345. 反转字符串中元音字母的位置 Reverse Vowels of a String

static public string ReverseVowels(string s) {
	Stack<char> vowelsStack = new Stack<char>();
	for (int i = 0; i < s.Length; i++) {
		char c = s[i];
		if (c == ‘a‘ || c == ‘e‘ || c == ‘i‘ || c == ‘o‘ || c == ‘u‘ ||
			c == ‘A‘ || c == ‘E‘ || c == ‘I‘ || c == ‘O‘ || c == ‘U‘) {
			vowelsStack.Push(c);
		}
	}
	string rsult = "";
	for (int i = 0; i < s.Length; i++) {
		char c = s[i];
		if (c == ‘a‘ || c == ‘e‘ || c == ‘i‘ || c == ‘o‘ || c == ‘u‘ ||
			c == ‘A‘ || c == ‘E‘ || c == ‘I‘ || c == ‘O‘ || c == ‘U‘) {
			rsult += vowelsStack.Pop();
		} else {
			rsult += c;
		}
	}
	return rsult;
}