Hexspeak — LeetCode 1271 Python Solution

The problem

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'}.

Example

Input

num = "257"

Output

"IOI"

Explanation

257 is 101 in hexadecimal.

Python solution

class Solution:
    def toHexspeak 🔒(self, num: str) -> str:
        s = set('ABCDEFIO')
        t = hex(int(num))[2:].upper().replace('0', 'O').replace('1', 'I')
        return t if all(c in s for c in t) else 'ERROR'

Complexity

Pattern: Math and Number Theory

Find the closed form, the invariant, or the modular identity — and skip the loop entirely. LeetCode 1271. Hexspeak is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Math.

The math and number theory guide has the Python template for the pattern and the 485 LeetCode problems that use it.

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