Codeforces Round 924 (Div. 2) |
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Finished |
Vasya has two hobbies — adding permutations$$$^{\dagger}$$$ to arrays and finding the most frequently occurring element. Recently, he found an array $$$a$$$ and decided to find out the maximum number of elements equal to the same number in the array $$$a$$$ that he can obtain after adding some permutation to the array $$$a$$$.
More formally, Vasya must choose exactly one permutation $$$p_1, p_2, p_3, \ldots, p_n$$$ of length $$$n$$$, and then change the elements of the array $$$a$$$ according to the rule $$$a_i := a_i + p_i$$$. After that, Vasya counts how many times each number occurs in the array $$$a$$$ and takes the maximum of these values. You need to determine the maximum value he can obtain.
$$$^{\dagger}$$$A permutation of length $$$n$$$ is an array consisting of $$$n$$$ distinct integers from $$$1$$$ to $$$n$$$ in arbitrary order. For example, $$$[2,3,1,5,4]$$$ is a permutation, but $$$[1,2,2]$$$ is not a permutation ($$$2$$$ appears twice in the array), and $$$[1,3,4]$$$ is also not a permutation ($$$n=3$$$ but there is $$$4$$$ in the array).
Each test consists of multiple test cases. The first line contains a single integer $$$t$$$ ($$$1 \leq t \leq 2 \cdot 10^4$$$) — the number of test cases. Then follows the description of the test cases.
The first line of each test case contains a single integer $$$n$$$ ($$$1 \le n \le 2 \cdot 10^5$$$) — the length of the array $$$a$$$.
The second line of each test case contains $$$n$$$ integers $$$a_1, a_2, \ldots, a_n$$$ ($$$1 \le a_i \le 10^9$$$) — the elements of the array $$$a$$$.
It is guaranteed that the sum of $$$n$$$ over all test cases does not exceed $$$2 \cdot 10^5$$$.
For each test case, output a single number — the maximum number of elements equal to the same number after the operation of adding a permutation.
721 247 1 4 13103 102 10451 101 1 100 151 10 100 1000 123 131000000000 999999997 999999999
2 2 3 2 1 1 2
In the first test case, it is optimal to choose $$$p = [2, 1]$$$. Then after applying the operation, the array $$$a$$$ will be $$$[3, 3]$$$, in which the number $$$3$$$ occurs twice, so the answer is $$$2$$$.
In the second test case, one of the optimal options is $$$p = [2, 3, 1, 4]$$$. After applying the operation, the array $$$a$$$ will be $$$[9, 4, 5, 5]$$$. Since the number $$$5$$$ occurs twice, the answer is $$$2$$$.
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