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 - 1is not allowed. - You cannot concatenate numbers together. For example, if the input is
[1, 2, 1, 2], we cannot write this as 12 + 12.