|Codeforces Round #570 (Div. 3)|
This problem is actually a subproblem of problem G from the same contest.
There are $$$n$$$ candies in a candy box. The type of the $$$i$$$-th candy is $$$a_i$$$ ($$$1 \le a_i \le n$$$).
You have to prepare a gift using some of these candies with the following restriction: the numbers of candies of each type presented in a gift should be all distinct (i. e. for example, a gift having two candies of type $$$1$$$ and two candies of type $$$2$$$ is bad).
It is possible that multiple types of candies are completely absent from the gift. It is also possible that not all candies of some types will be taken to a gift.
Your task is to find out the maximum possible size of the single gift you can prepare using the candies you have.
You have to answer $$$q$$$ independent queries.
If you are Python programmer, consider using PyPy instead of Python when you submit your code.
The first line of the input contains one integer $$$q$$$ ($$$1 \le q \le 2 \cdot 10^5$$$) — the number of queries. Each query is represented by two lines.
The first line of each query contains one integer $$$n$$$ ($$$1 \le n \le 2 \cdot 10^5$$$) — the number of candies.
The second line of each query contains $$$n$$$ integers $$$a_1, a_2, \dots, a_n$$$ ($$$1 \le a_i \le n$$$), where $$$a_i$$$ is the type of the $$$i$$$-th candy in the box.
It is guaranteed that the sum of $$$n$$$ over all queries does not exceed $$$2 \cdot 10^5$$$.
For each query print one integer — the maximum possible size of the single gift you can compose using candies you got in this query with the restriction described in the problem statement.
3 8 1 4 8 4 5 6 3 8 16 2 1 3 3 4 3 4 4 1 3 2 2 2 4 1 1 9 2 2 4 4 4 7 7 7 7
3 10 9
In the first query, you can prepare a gift with two candies of type $$$8$$$ and one candy of type $$$5$$$, totalling to $$$3$$$ candies.
Note that this is not the only possible solution — taking two candies of type $$$4$$$ and one candy of type $$$6$$$ is also valid.