C. Sort Zero
greedy; sortings
An array is sorted if it has no inversionsA Young BoyYou are given an array of \(n\) positive integers \(a_1,a_2,\ldots,a_n\). In one operation you do the following: Choose any integer \(x\). For all \(i\) such that \(a_i = x\), do \(a_i := 0\) (assign \(0\) to \(a_i\)). Find the minimum number of operations required to sort the array in non-decreasing order.
Each test contains multiple test cases. The first line contains the number of test cases \(t\) (\(1 \le t \le 10^4\)). Description of the test cases follows.The first line of each test case contains a single integer \(n\) (\(1 \le n \le 10^5\)).The second line of each test case contains \(n\) positive integers \(a_1,a_2,\ldots,a_n\) (\(1 \le a_i \le n\)).It is guaranteed that the sum of \(n\) over all test cases does not exceed \(10^5\).
For each test case print one integer — the minimum number of operations required to sort the array in non-decreasing order.
In the first test case, you can choose \(x = 3\) for the operation, the resulting array is \([0, 0, 2]\).In the second test case, you can choose \(x = 1\) for the first operation and \(x = 3\) for the second operation, the resulting array is \([0, 0, 0, 0]\).