Codeforces Round 945 (Div. 2) |
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Finished |
Today, Cat and Fox found an array $$$a$$$ consisting of $$$n$$$ non-negative integers.
Define the loneliness of $$$a$$$ as the smallest positive integer $$$k$$$ ($$$1 \le k \le n$$$) such that for any two positive integers $$$i$$$ and $$$j$$$ ($$$1 \leq i, j \leq n - k +1$$$), the following holds: $$$$$$a_i | a_{i+1} | \ldots | a_{i+k-1} = a_j | a_{j+1} | \ldots | a_{j+k-1},$$$$$$ where $$$x | y$$$ denotes the bitwise OR of $$$x$$$ and $$$y$$$. In other words, for every $$$k$$$ consecutive elements, their bitwise OR should be the same. Note that the loneliness of $$$a$$$ is well-defined, because for $$$k = n$$$ the condition is satisfied.
Cat and Fox want to know how lonely the array $$$a$$$ is. Help them calculate the loneliness of the found array.
Each test consists of multiple test cases. The first line contains a single integer $$$t$$$ ($$$1 \leq t \leq 10^4 $$$) — the number of test cases. The description of the test cases follows.
The first line of each test case contains one integer $$$n$$$ ($$$1 \leq n \leq 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$$$ ($$$0 \leq a_i < 2^{20}$$$) — the elements of the array.
It is guaranteed that the sum of $$$n$$$ over all test cases doesn't exceed $$$10^5$$$.
For each test case, print one integer — the loneliness of the given array.
71032 2 231 0 253 0 1 4 252 0 4 0 270 0 0 0 1 2 480 1 3 2 2 1 0 3
1 1 3 4 4 7 3
In the first example, the loneliness of an array with a single element is always $$$1$$$, so the answer is $$$1$$$.
In the second example, the OR of each subarray of length $$$k = 1$$$ is $$$2$$$, so the loneliness of the whole array is $$$1$$$.
In the seventh example, it's true that $$$(0 | 1 | 3) = (1 | 3 | 2) = (3 | 2 | 2) = (2 | 2 | 1) = (2 | 1 | 0) = (1 | 0 | 3) = 3$$$, so the condition is satisfied for $$$k = 3$$$. We can verify that the condition is not true for any smaller $$$k$$$, so the answer is indeed $$$3$$$.
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