You have 4 cards each containing a number from 1 to 9. You need to judge whether they could operated through *, /, +, -, (, ) to get the value of 24. Example 1: Input: [4, 1, 8, 7] Output: True Explanation: (8-4) * (7-1) = 24 Example 2: Input: [1, 2, 1, 2] Output: False Note: The division operator / represents real division, not integer division. For example, 4 / (1 - 2/3) = 12. Every operation done is between two numbers. In particular, we cannot use - as a unary operator. For example, with [1, 1, 1, 1] as input, the expression -1 - 1 - 1 - 1 is not allowed. You cannot concatenate numbers together. For example, if the input is [1, 2, 1, 2], we cannot write this as 12 + 12.