Check if a string which represents a math exercise is balanced in terms of parentheses

Remove spaces from a string

Question

Check if a string which represents a math exercise is balanced in terms of parentheses

Remove spaces from a string

nir · Accepted Answer

public class CheckParenthesesBalanced
{
	public static void main(String[] args)
	{
		String s = "n({})ir";
		System.out.println(isBalanced(s));
	}

	private static boolean isBalanced(String str)
	{
		Stack stack = new Stack();
		final Set openParentheses = Set.of('(', '{', '[');
		final Set closedParentheses = Set.of(')', '}', ']');
		for (int i = 0; i < str.length(); i++) {
			char c = str.charAt(i);
			if (openParentheses.contains(c)) {
				stack.push(c);
			}
			else if (closedParentheses.contains(c)) {
				Character popped = stack.pop();
				if (popped != getComplementBracket(c)) {
					return false;
				}
			}
		}
		return true;
	}

	private static char getComplementBracket(char c)
	{
		switch (c) {
			case ')':
				return '(';
			case '}':
				return '{';
			case ']':
				return '[';
			default:
				throw new IllegalArgumentException("no bracket for char "+c);
		}
	}
}

om · Answer

static void Main(string[] args)
    {
        bool error = false;
        var str = "( a[i]+{-1}*(8-9) )";
        Stack stack = new Stack();
        foreach (var item in str.ToCharArray())
        {
            if (item == '(' || item == '{' || item == '[')
            {
                stack.Push(item);
            }
            else if(item == ')' || item == '}' || item == ']')
            {
                if (stack.Peek() != GetComplementBracket(item))
                {
                    error = true;
                    break;
                }
            }
        }

        if (error)
            Console.WriteLine("Incorrect brackets");
        else
            Console.WriteLine("Brackets are fine");
        Console.ReadLine();
    }

    private static char GetComplementBracket(char item)
    {
        switch (item)
        {
            case ')':
                return '(';
            case '}':
                return '{';
            case ']':
                return '[';
            default:
                return ' ';
        }
    }

om · Answer

Regex.Replace(str, @"\s+", "")

Microsoft

Microsoft Interview Question

Interview Answers

Want the inside scoop on your own company?

Bowls

Followed companies

Job searches