private int operate(char operator, int x, int y) {
        switch (operator) {
            case '+':
                return x + y;
            case '-':
                return x - y;
            case '*':
                return x*y;
            case '/':
                return x/y;
            default:
                throw new IllegalArgumentException();
        }
    }
Date 01/07/2016
@author Tushar Roy

Given an expression with +, -, * and / operators. Tell if expression can evaluate to given result with different
parenthesis combination.
e.g expresson is 2*3-1 and result is 4, function should return true since 2*(3-1) evaluate to 4.

Time complexity is O(n^5)
Space complexity is O(n^3)
src/com/interview/dynamic/ExpressionEvaluation.java