Enter an expression (expressed as a string) and find the value of this expression.

When brushing algorithm problems , Come across a problem , Make a note of , The title is like this ：

Enter an expression （ Represented by string ）, Find the value of this expression .
Ensure that the valid characters in the string include [‘0’-‘9’],‘+’,‘-’, ‘*’,‘/’ ,‘(’, ‘)’,‘[’, ‘]’,‘{’ ,‘}’. And the expression must be legal .

Input description ：
Enter an arithmetic expression

Output description ：
Get the calculation results

Input ：
3+2*{1+2*[-4/(8-6)+7]}

Output ：
25

Look at the solution , as follows ：

		Scanner scan = new  Scanner(System.in);
        String input = s;
        input = input.replace("[","(");
        input = input.replace("{","(");
        input = input.replace("}",")");
        input = input.replace("]",")");
        ScriptEngine scriptEngine = new ScriptEngineManager().getEngineByName("nashorn");
        try {
    
            System.out.println(scriptEngine.eval(input));
        } catch (ScriptException e) {
    
            throw new RuntimeException(e);
        }

forehead , Beyond my imagination , This ScriptEngine It's amazing . Got it .

The general purpose is mainly to be able to parse general expressions , such as X >= 1（X Pass in as a parameter ） Such an expression , Also can use js Function syntax for , Create a java The same function exists in memory and can be called at any time , It is also possible to js Objects in are directly converted to java object .

Reference link ：Java use ScriptEngine Parsing script