Even Digits

Design a hardware module for the Even Digits problem.

Given a non-negative integer n, find the minimum amount you must add or subtract so that the resulting number contains only even decimal digits.

Digits 0, 2, 4, 6, and 8 are even. Digits 1, 3, 5, 7, and 9 are odd.

Your task is to output the minimum distance from n to any number whose decimal representation uses only even digits.

Hardware I/O Encoding

• n is a scalar unsigned 32-bit integer input
• the output is a single unsigned 32-bit integer
• the output value is the minimum absolute difference between n and any all-even-digit number

Examples

Example 1

• input n = 42
• output: 0

The decimal digits of 42 are already all even.

Example 2

• input n = 11
• output: 3

The closest all-even-digit numbers are 8 and 20, with distances 3 and 9. The minimum is 3.

Example 3

• input n = 2018
• output: 2

The closest all-even-digit number is 2020.

Source: Google Kick Start 2018 Round A - Even Digits