CF1975C Chamo and Mocha's Array
Description
Mocha likes arrays, so before her departure, Chamo gave her an array $ a $ consisting of $ n $ positive integers as a gift.
Mocha doesn't like arrays containing different numbers, so Mocha decides to use magic to change the array. Mocha can perform the following three-step operation some (possibly, zero) times:
1. Choose indices $ l $ and $ r $ ( $ 1 \leq l < r \leq n $ )
2. Let $ x $ be the median $ ^\dagger $ of the subarray $ [a_l, a_{l+1},\ldots, a_r] $
3. Set all values $ a_l, a_{l+1},\ldots, a_r $ to $ x $
Suppose $ a=[1,2,3,4,5] $ initially:
- If Mocha chooses $ (l,r)=(3,4) $ in the first operation, then $ x=3 $ , the array will be changed into $ a=[1,2,3,3,5] $ .
- If Mocha chooses $ (l,r)=(1,3) $ in the first operation, then $ x=2 $ , the array will be changed into $ a=[2,2,2,4,5] $ .
Mocha will perform the operation until the array contains only the same number. Mocha wants to know what is the maximum possible value of this number.
$ ^\dagger $ The median in an array $ b $ of length $ m $ is an element that occupies position number $ \lfloor \frac{m+1}{2} \rfloor $ after we sort the elements in non-decreasing order. For example, the median of $ [3,1,4,1,5] $ is $ 3 $ and the median of $ [5,25,20,24] $ is $ 20 $ .
Input Format
Each test contains multiple test cases. The first line contains the number of test cases $ t $ ( $ 1\leq t\leq 500 $ ). The description of the test cases follows.
The first line of each test case contains a single integer $ n $ ( $ 2\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 $ ( $ 1\leq a_i \leq 10^9 $ ) — the elements of the array $ a $ .
It is guaranteed that the sum of $ n $ over all test cases does not exceed $ 10^5 $ .
Output Format
For each test case, output the maximum value of the number.
Explanation/Hint
In the first test case, $ a=[1,2] $ . Mocha can only choose the interval $ (l,r)=(1,2) $ . The array will be changed to $ a=[1,1] $ . Therefore, the answer is $ 1 $ .
In the second test case, Mocha can perform the following operations:
- Choose the interval $ (l,r)=(4,5) $ , then $ a=[1,2,3,4,4] $ .
- Choose the interval $ (l,r)=(3,5) $ , then $ a=[1,2,4,4,4] $ .
- Choose the interval $ (l,r)=(1,5) $ , then $ a=[4,4,4,4,4] $ .
The array contains only the same number, which is $ 4 $ . It can be proven that the maximum value of the final number cannot be greater than $ 4 $ .