Auto add parentheses to math operation string randomly?

Question

Do you have any idea to add parentheses to math operation string automatically and randomly?

For example.

A given operation string:

57 x 40 - 14 + 84 ÷ 19

I need to auto add parentheses randomly in above string.

so it becomes:

(57 x 40) - 14 + (84 ÷ 19) or

(57 x 40) - (14 + 84 ÷ 19) or

57 x (40 - 14) + (84 ÷ 19) or

57 x (40 - 14 + 84 ÷ 19) or

57 x (40 - (14 + 84) ÷ 19)

It really appreciated for the help!!

Mick,

Select an operator at random, move left and right until you've got a random number of numbers. Repeat at random. What's the problem ? — High Performance Mark, May 14 '12 at 12:38
Have you considered the alternative of picking each pair of numbers and doing each operation on them to produce 4 sets of n-1 numbers and repeating that until you have all possible results? Or do you actually need to have each of the possible strings with parenthesis? — Helen, May 14 '12 at 12:59

score 1 · Accepted Answer · answered May 14 '12 at 12:57

I assumed three things:

There is always space char between number and operator
All numbers are integers (you can easily change that to other types)
Everything that is not number is operator

Example in C#:

Math m = new Math(); 
string p = m.DoStuff("57 x 40 - 14 + 84 ÷ 19");
Console.WriteLine(p);

class Math
{       
    internal string DoStuff(string p)
    {
        bool isParOpen = false;
        Random rnd = new Random();
        StringBuilder result = new StringBuilder();
        int i;

        string[] stack = p.Split(' ');
        foreach (var item in stack)
        {
            if (int.TryParse(item, out i))
            {
                if (rnd.Next(2) == 1)
                {
                    result.Append(isParOpen ? string.Format("{0}) ", item) : string.Format("({0} ", item));
                    isParOpen = !isParOpen;
                }
                else
                {
                    result.Append(item).Append(" ");
                }
            }
            else
            {
                result.Append(item).Append(" ");
            }
        }

        if (isParOpen)
        {
            result.Append(")");
        }

        return result.ToString();
    }
}

Appreciated for your help, Tschareck! Thank you! Mick, – Mick May 14 '12 at 13:13 — Mick, May 14 '12 at 13:13

score 0 · Answer 2 · edited May 23 '17 at 10:34

0

If you handle the mathematical expresion as a String, you can add parenthesis randomly (Eg. add random chars to a string), and then using an script engine, you can evaluate the expresion.

edited May 23 '17 at 10:34

Community

1
1

answered May 14 '12 at 12:42

Oscar Castiblanco

1,626
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31

Auto add parentheses to math operation string randomly?

2 Answers2