leetcode2605: Form Smallest Number From Two Digit Arrays

### Description

Given two arrays of unique digits nums1 and nums2, return the smallest number that contains at least one digit from each array.

#### Example 1:

Input: nums1 = [4,1,3], nums2 = [5,7]
Output: 15
Explanation: The number 15 contains the digit 1 from nums1 and the digit 5 from nums2. It can be proven that 15 is the smallest number we can have.

#### Example 2:

Input: nums1 = [3,5,2,6], nums2 = [3,1,7]
Output: 3
Explanation: The number 3 contains the digit 3 which exists in both arrays.

#### Constraints:

1 <= nums1.length, nums2.length <= 9
1 <= nums1[i], nums2[i] <= 9
All digits in each array are unique.