2025-08-16 07:09:43 +0000 UTC

class Solution:
    def maximum69Number (self, num: int) -> int:
        digits = []
        while num > 0:
            digits.append(num % 10)
            num //= 10
        digits.reverse()
        for i in range(len(digits)):
            if digits[i] == 6:
                digits[i] = 9
                break
        res = 0
        count = 0
        while digits:
            res += digits.pop() * (10 ** count)
            count += 1
        return res