1271. Hexspeak

class Solution:
    def toHexspeak(self, num: str) -> str:
        """
        1. convert num  -> hex 
        2. map hex digit with O~A
        3. get rem of each mod 16, cache rem into arr
        4. convert 
        tc O(lgN)   N: value of num   sc  O(lgN)
        """
        d = {1:'I',0:'O',10:"A",11: "B",12: "C", 13:"D", 14:"E", 15:"F"}
        x = []
        y = int(num)
        rem = y%16
        if rem not in d:
            return "ERROR"
        while y>0:
            x.append(y%16)
            y = (y-y%16)/16 
        x = x[::-1]
        for i,a in enumerate(x):
            if a not in d:
                return "ERROR" # early termination
            x[i] = d[a]
        return ''.join(x)

# tc, sc  O(num.length()) 
class Solution:
    def toHexspeak(self, num: str) -> str:
        s = hex(int(num)).upper()[2 :].translate(str.maketrans('01', 'OI'))
        return 'ERROR' if any(c.isdigit() for c in s) else s