Balanced Parentheses with a Stack

Console.WriteLine(IsBalanced("{[()]}"));      // True
Console.WriteLine(IsBalanced("{[(])}"));      // False
Console.WriteLine(IsBalanced("(("));          // False
Console.WriteLine(IsBalanced(""));            // True

// O(n) time. A closer must match the most recent opener, which is exactly what a stack gives you.
static bool IsBalanced(string text)
{
    var stack = new Stack<char>();
    foreach (char c in text)
    {
        if (c is '(' or '[' or '{')
        {
            stack.Push(c);
        }
        else if (c is ')' or ']' or '}')
        {
            if (stack.Count == 0) return false;
            char open = stack.Pop();
            bool matches = (c == ')' && open == '(') || (c == ']' && open == '[') || (c == '}' && open == '{');
            if (!matches) return false;
        }
    }
    return stack.Count == 0;
}