CF1550D Excellent Arrays
Description
Let's call an integer array $ a_1, a_2, \dots, a_n $ good if $ a_i \neq i $ for each $ i $ .
Let $ F(a) $ be the number of pairs $ (i, j) $ ( $ 1 \le i < j \le n $ ) such that $ a_i + a_j = i + j $ .
Let's say that an array $ a_1, a_2, \dots, a_n $ is excellent if:
- $ a $ is good;
- $ l \le a_i \le r $ for each $ i $ ;
- $ F(a) $ is the maximum possible among all good arrays of size $ n $ .
Given $ n $ , $ l $ and $ r $ , calculate the number of excellent arrays modulo $ 10^9 + 7 $ .
Input Format
The first line contains a single integer $ t $ ( $ 1 \le t \le 1000 $ ) — the number of test cases.
The first and only line of each test case contains three integers $ n $ , $ l $ , and $ r $ ( $ 2 \le n \le 2 \cdot 10^5 $ ; $ -10^9 \le l \le 1 $ ; $ n \le r \le 10^9 $ ).
It's guaranteed that the sum of $ n $ doesn't exceed $ 2 \cdot 10^5 $ .
Output Format
For each test case, print the number of excellent arrays modulo $ 10^9 + 7 $ .
Explanation/Hint
In the first test case, it can be proven that the maximum $ F(a) $ among all good arrays $ a $ is equal to $ 2 $ . The excellent arrays are:
1. $ [2, 1, 2] $ ;
2. $ [0, 3, 2] $ ;
3. $ [2, 3, 2] $ ;
4. $ [3, 0, 1] $ .