Given two integer lists, list_a and list_b, return a list containing the unique elements that appear in both lists. The order of elements in the output list does not matter.
Example 1
Input: list_a = [7, 3, 5, 7], list_b = [5, 7, 7]
Output: [5, 7]
Explanation: Both 5 and 7 appear in both lists. Output order does not matter.
Example 2
Input: list_a = [10, 20, 30], list_b = [40, 50, 60]
Output: []
Explanation: No common elements between the lists.
Example 3
Input: list_a = [2, 2, 2], list_b = [2, 2]
Output: [2]
Explanation: 2 is the only common element, returned uniquely.
Constraints
Case 1
Input: list_a = [1, 4, 6, 8], list_b = [6, 8, 9, 10]
Expected: [6, 8]
Case 2
Input: list_a = [0, 1, 2, 3], list_b = [3, 4, 5, 6]
Expected: [3]
Case 3
Input: list_a = [1000], list_b = [1000, 999]
Expected: [1000]
Case 4
Input: list_a = [11, 22, 33, 44], list_b = [22, 44, 55, 66]
Expected: [22, 44]
Case 5
Input: list_a = [5, 5, 5, 5], list_b = [5]
Expected: [5]