Unique 3-Digit Even Numbers
You are given an array of digits called digits. Your task is to determine the number of distinct three-digit even numbers that can be formed using these digits.
Note: Each copy of a digit can only be used once per number, and there may not be leading zeros.
Example 1
Input
digits = [1,2,3,4]Output
12The 12 distinct 3-digit even numbers that can be formed are 124, 132, 134, 142, 214, 234, 312, 314, 324, 342, 412, and 432; 222 cannot be formed because there is only 1 copy of the digit 2.
Example 2
Input
digits = [0,2,2]Output
2The only 3-digit even numbers that can be formed are 202 and 220; the digit 2 can be used twice because it appears twice in the array.
Constraints
- 3 <= digits.length <= 10
- 0 <= digits[i] <= 9