Remove duplicate elements from an array (without?

Short answer: LINQ Distinct()) Logic Use a HashSet to track seen elements. Add elements only if they are not already present. int[] arr = { 1, 2, 3, 2, 4, 1 }; HashSet<int> set = new HashSet<int>(); List<int> result = new List<int>(); foreach (int num in arr) { if (!set.Contains(num)) { set.Add(num); result.Add(num); } } Why this works: HashSet ensures uniqueness with O(1) lookup.

Example code

LINQ Distinct()) Logic Use a HashSet to track seen elements. Add elements only if they are not already present. int[] arr = { 1, 2, 3, 2, 4, 1 };
HashSet<int> set = new HashSet<int>();
List<int> result = new List<int>();
foreach (int num in arr)
{
if (!set.Contains(num))
{ set.Add(num); result.Add(num); }
} Why this works: HashSet ensures uniqueness with O(1) lookup.

Real-world example (ShopNest)

In coding rounds, state complexity aloud, write a clear ShopNest-flavored example (orders, carts), then handle edge cases (empty list, null, overflow).

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.