Can a hash table be effectively used to determine unique elements in an array or list?

Yes, a hash table (in Go, this is a map) can be effectively used to identify unique elements in an array or list. The idea is to iterate over all elements and add them to the map as keys. Since keys in a map are unique, this allows for quick filtering of duplicate elements.

Example in Go:

func uniqueElements(arr []int) []int {
    seen := make(map[int]bool)
    var result []int
    for _, v := range arr {
        if !seen[v] {
            seen[v] = true
            result = append(result, v)
        }
    }
    return result
}

This approach works in O(n) time, where n is the number of elements, which is much more efficient than nested loops with O(n²).