CF1935D Exam in MAC

The Master's Assistance Center has announced an entrance exam, which consists of the following. The candidate is given a set $ s $ of size $ n $ and some strange integer $ c $ . For this set, it is needed to calculate the number of pairs of integers $ (x, y) $ such that $ 0 \leq x \leq y \leq c $ , $ x + y $ is not contained in the set $ s $ , and also $ y - x $ is not contained in the set $ s $ . Your friend wants to enter the Center. Help him pass the exam!

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. The description of the test cases follows. The first line of each test case contains two integers $ n $ and $ c $ ( $ 1 \leq n \leq 3 \cdot 10^5 $ , $ 1 \leq c \leq 10^9 $ ) — the size of the set and the strange integer. The second line of each test case contains $ n $ integers $ s_1, s_2, \ldots, s_{n} $ ( $ 0 \leq s_1 < s_2 < \ldots < s_{n} \leq c $ ) — the elements of the set $ s $ . It is guaranteed that the sum of $ n $ over all test cases does not exceed $ 3 \cdot 10^5 $ .

For each test case, output a single integer — the number of suitable pairs of integers.

In the first test case, the following pairs are suitable: $ (0, 0) $ , $ (2, 2) $ , $ (3, 3) $ . In the third test case, the following pairs are suitable: $ (0, 1) $ , $ (0, 2) $ , $ (0, 4) $ , $ (1, 3) $ , $ (2, 6) $ , $ (3, 4) $ , $ (3, 5) $ , $ (4, 5) $ , $ (4, 6) $ , $ (5, 6) $ .