easyArraysPattern: Hashing
Count Unique Elements Solution
Problem Statement
You are given an array of integers `nums`. Write a function to count the number of unique elements in the array.
Examples
Example 1:
Input:[1, 2, 3, 2, 1]
Output:3
Explanation: There are 3 unique identifiers: 1, 2, and 3
Example 2:
Input:[4, 4, 4, 4]
Output:1
Explanation: There is only 1 unique identifier: 4
Example 3:
Input:[]
Output:0
Explanation: There are no unique identifiers in an empty array
Constraints
- The array will not be null.
- The array will have at least two elements.
- Duplicates may appear multiple times.
Time: O(n) Space: O(n)
Use a set data structure to store unique identifiers with a time complexity of O(n)
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