CF1842C Tenzing and Balls

Enjoy erasing Tenzing, identified as Accepted! Tenzing has $ n $ balls arranged in a line. The color of the $ i $ -th ball from the left is $ a_i $ . Tenzing can do the following operation any number of times: - select $ i $ and $ j $ such that $ 1\leq i < j \leq |a| $ and $ a_i=a_j $ , - remove $ a_i,a_{i+1},\ldots,a_j $ from the array (and decrease the indices of all elements to the right of $ a_j $ by $ j-i+1 $ ). Tenzing wants to know the maximum number of balls he can remove.

Each test contains multiple test cases. The first line of input contains a single integer $ t $ ( $ 1\leq t\leq 10^3 $ ) — the number of test cases. The description of test cases follows. The first line contains a single integer $ n $ ( $ 1\leq n\leq 2\cdot 10^5 $ ) — the number of balls. The second line contains $ n $ integers $ a_1,a_2,\ldots,a_n $ ( $ 1\leq a_i \leq n $ ) — the color of the balls. It is guaranteed that sum of $ n $ of all test cases will not exceed $ 2\cdot 10^5 $ .

For each test case, output the maximum number of balls Tenzing can remove.

In the first example, Tenzing will choose $ i=2 $ and $ j=3 $ in the first operation so that $ a=[1,3,3] $ . Then Tenzing will choose $ i=2 $ and $ j=3 $ again in the second operation so that $ a=[1] $ . So Tenzing can remove $ 4 $ balls in total. In the second example, Tenzing will choose $ i=1 $ and $ j=3 $ in the first and only operation so that $ a=[2] $ . So Tenzing can remove $ 3 $ balls in total.