Find Duplicates in an Array

Given an array ARR of size 'N', where each integer is in the range from 0 to N - 1, identify all elements that appear more than once.

Return the duplicate elements in any order. If no duplicates are found, return an empty array.

Example:

Input:

T = 2
N = 5, ARR = [0, 3, 1, 2, 3]
N = 3, ARR = [0, 1, 2]

Output:

3

Explanation:

For the first test case, 3 is repeated. In the second test case, no duplicates are present.

Constraints:

• 1 <= T <= 10^2
• 1 <= N <= 10^4
• 0 <= ARR[i] <= N - 1
• Time Limit: 1 sec