Count Supersequences

Description:

Input:

The first line of the input contains a single integer $$$t$$$ ($$$1 \le t \le 10^4$$$) — the number of test cases. The description of the test cases follows.

The first line of each test case contains three integers $$$n$$$, $$$m$$$, $$$k$$$ ($$$1 \le n \le 2\cdot 10^5$$$, $$$n \le m \le 10^9$$$, $$$1 \le k \le 10^9$$$) — the size of $$$a$$$, the size of $$$b$$$, and the maximum value allowed in the arrays, respectively.

The next line of each test case contains $$$n$$$ integers $$$a_1, a_2, \ldots a_n$$$ ($$$1\le a_i \le k$$$) — the elements of the array $$$a$$$.

It is guaranteed that the sum of $$$n$$$ over all test cases does not exceed $$$2\cdot 10^5$$$.

Output:

For each test case, output a single integer — the number of suitable arrays $$$b$$$, modulo $$$10^9+7$$$.

Sample Input:

7
1 1000000 1
1
3 4 3
1 2 2
5 7 8
1 2 3 4 1
6 6 18
18 2 2 5 2 16
1 10 2
1
8 10 1234567
1 1 2 1 2 2 2 1
5 1000000000 1000000000
525785549 816356460 108064697 194447117 725595511

Sample Output:

1
9
1079
1
1023
906241579
232432822

Note:

For the first example, since $$$k=1$$$, there is only one array of size $$$m$$$ consisting of the integers $$$[1, k]$$$. This array ($$$[1, 1, \ldots, 1]$$$) contains the original array as a subsequence, so the answer is 1.

For the second example, the $$$9$$$ arrays are $$$[1, 1, 2, 2]$$$, $$$[1, 2, 1, 2]$$$, $$$[1, 2, 2, 1]$$$, $$$[1, 2, 2, 2]$$$, $$$[1, 2, 2, 3]$$$, $$$[1, 2, 3, 2]$$$, $$$[1, 3, 2, 2]$$$, $$$[2, 1, 2, 2]$$$, $$$[3, 1, 2, 2]$$$.

For the fourth example, since $$$m=n$$$, the only array of size $$$m$$$ that contains $$$a$$$ as a subsequence is $$$a$$$ itself.