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A decimal number can be converted to its Hexspeak representation by first converting it to an uppercase hexadecimal string, then replacing all occurrences of the digit 0 with the letter O, and the digit 1 with the letter I. Such a representation is valid if and only if it consists only of the letters in the set {"A", "B", "C", "D", "E", "F", "I", "O"}.
Given a string num representing a decimal integer N, return the Hexspeak representation of N if it is valid, otherwise return "ERROR".
Example 1:
Input: num = "257"
Output: "IOI"
Explanation: 257 is 101 in hexadecimal.
Example 2:
Input: num = "3"
Output: "ERROR"
Constraints:
1 <= N <= 10^12
- There are no leading zeros in the given string.
- All answers must be in uppercase letters.
[Math]
[String]
Hints
Hint 1
Convert the given number to hexadecimal.
Hint 2
Replace all 0 and 1 with 'O' and 'I'.
Hint 3
Check if the final string has any numerical digits.