How should I practice Process Queries on Cart?

Start by reading the full statement, solve the visible examples, then compare the pattern against related Amazon online assessment problems in FastPrep.

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FastPrep tags this as a Amazon online assessment coding practice problem when the problem catalog has that company and stage context.

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Process Queries on Cart

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AmazonNEW GRADOA

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Problem statement

As an aspiring developer at Amazon, you are building a prototype for a cart management service.

There is an array of integers, items, that represents the item ids present in the cart initially.

Given an array of q integers, query, your service must perform as follows.

Each integer is an item id to be added to or removed from the cart.

If the query integer is positive, add the integer representing an item id to the back of the cart.

If the integer is negative, remove the first occurrence of the integer from the cart.

Report an array that represents the final cart after processing all the queries.

It is guaranteed that the final cart is non-empty and the integers in the integer

Function

processQueriesOnCart(items: int[], query: int[]) → int[]

Complete the function processQueriesOnCart in the editor below.

processQueriesOnCart has the following parameters:

int items[n]: items initially in the cart
int query[q]: items to add or remove

Examples

Example 1

items = [1, 2, 1, 2, 1]query = [-1, -1, 3, 4, -3]return = [2, 2, 1, 4]

Initially, there are n = 5 items in the cart represented as cart = [1,2,1,2,1] and queries = [-1,-1,3,4,-3]

Query	Task	Cart
-1	Delete first 1 from cart	[2,1,2,1]
-1	Delete first 1 from cart	[2,2,1]
3	Append 3 to cart	[2,2,1,3]
4	Append 4 to cart	[2,2,1,3,4]
-3	Delete first 3 from cart	[2,2,1,4]

Report [2,2,1,4] as the final cart.

Example 2

items = [5, 1, 2, 2, 4, 6]query = [1, -2, -1, -1]return = [5, 2, 4, 6]

items = [5, 1, 2, 2, 4, 6] queries = [1, -2, -1, -1]

Query	Task	Cart
1	Append 1 to cart	[5, 1, 2, 2, 4, 6, 1]
-2	Delete first 2 from cart	[5, 1, 2, 4, 6, 1]
-1	Delete first 1 from cart	[5, 2, 4, 6, 1]
-1	Delete first 1 from cart	[5, 2, 4, 6]

Report [5, 2, 4, 6] as the final cart.

Constraints

1 <= n, q <= 2 * 10^5
1 <= items[i] <= 10^9
-10^9 <= query[i] <= 10^9
It is guaranteed that query[i] != 0