X1503: Count Distinct

Problem Description

Write a method countDistinct that takes an array of integers and returns the count of distinct (unique) numbers present in the array.

Method Signature:

public int countDistinct(int[] nums)

You must use a TreeSet<Integer> as the class to store the set.
Store each number in the array, ensuring only unique values are stored.
Return the size of the set, which will give the count of distinct numbers.
The array will contain at least one integer.
The array may contain both positive and negative integers.
The TreeSet will automatically handle duplicate values, so you only need to focus on inserting numbers.

Examples:

countDistinct({1, 2, 3, 2, 4, 1}) -> 4

countDistinct({7, 7, 7, 7, 7, 7}) -> 1

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