Solution: Finding 3-Digit Even Numbers

Statement

Given an integer array digits, form all unique three digit positive even integers that can be built by selecting exactly three elements from digits without reusing an element more times than it appears in digits.

Return these integers in increasing order. A valid number must not have a leading zero, and its last digit must be even.

Note: Each occurrence of a value in digits can be used at most once per constructed number, so repeated values in digits allow repeated use up to their frequency.

Constraints:

• $3 \leq$ digits.length ...