You have a list of orders for a particular user. I want to remove duplicate orders. How would you do that?

To remove duplicate orders from a list, you can use a set or dictionary to track seen order identifiers. Iterate through the list, and for each order, check if its unique key (e.g., order_id) is already in the set. If not, add the key to the set and keep the order; otherwise skip it. This approach runs in O(n) time and O(n) space. Example in Python:

orders = [
    {'order_id': 1, 'item': 'A'},
    {'order_id': 2, 'item': 'B'},
    {'order_id': 1, 'item': 'A'},
    {'order_id': 3, 'item': 'C'}
]
seen = set()
unique_orders = []
for order in orders:
    if order['order_id'] not in seen:
        seen.add(order['order_id'])
        unique_orders.append(order)
print(unique_orders)

Output:

[{'order_id': 1, 'item': 'A'}, {'order_id': 2, 'item': 'B'}, {'order_id': 3, 'item': 'C'}]