Check if the parenthesis/brackets are balanced

balanced_parenthesis.cs

public static bool balanced_brackets(string S)
{
    var open = new List<char>(){'(', '{', '['};

    var stack = new Stack<char>();

    foreach (var i in S)
    {
        if (open.Contains(i)) stack.Push(i);
        
        else
        {
            if (stack.Count == 0) return false;
            bool valid = true;
            
            switch (i)
            {
                case ')':
                    if (stack.Peek() != '(') valid = false;
                    break;
                case '}':
                    if (stack.Peek() != '{') valid = false;
                    break;
                case ']':
                    if (stack.Peek() != '[') valid = false;
                    break;
            }
            
            if (valid) stack.Pop();
            else return false;
        }
    }
    
    return stack.Count == 0;
}

balanced_parenthesis.java

public boolean isValid(String s) {
        
    Stack<Character> stack = new Stack<Character>();

    for(int i = 0 ; i < s.length(); i++){

        char c = s.charAt(i);

        if(c == '(' || c == '{' || c == '[') stack.push(c);

        else  {
            if(stack.size() == 0) return false;

            boolean valid = true;
            switch (c)
            {
                case ')':
                    if (stack.peek() != '(') valid = false;
                    break;
                case '}':
                    if (stack.peek() != '{') valid = false;
                    break;
                case ']':
                    if (stack.peek() != '[') valid = false;
                    break;
            }
            if (valid) stack.pop();
            else return false;
        }
    }

    return stack.isEmpty();
}