Unique Values in C++

Given a vector of integers nums, return how many different values it has.

A value that appears several times counts only once.

Example 1:

Input: nums = [4, 7, 4, 1, 7]
Output: 3
Explanation: The different values are 4, 7 and 1. The second 4 and the second 7 are repeats, so they don't count again.

Example 2:

Input: nums = [5, 5, 5]
Output: 1
Explanation: Every number is 5, so there is only one different value.

Example 3:

Input: nums = [-2, 0, 3, 8]
Output: 4
Explanation: No value repeats, so every number counts.

Constraints:

• nums has at least one number.
• Every number is between -10⁹ and 10⁹.