2025-08-21 13:42:44 +0000 UTC

class Solution:
    def countBeautifulPairs(self, nums: List[int]) -> int:
        def check(num1: int, num2: int) -> bool: 
            first, last = 0, num2 % 10
            while num1 > 0:
                first = num1 % 10
                num1 //= 10
            return math.gcd(first, last) == 1
        res = 0
        for i in range(len(nums)):
            for j in range(i + 1, len(nums)):
                if check(nums[i], nums[j]):
                    res += 1
        return res