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19

Count Subsequences

Difficulty: MEDIUM
Contributed By
Avg. time to solve
30 min
Success Rate
60%

Problem Statement

You have been given an integer array/list 'ARR' of size 'N'. Your task is to return the total number of those subsequences of the array in which all the elements are equal.

A subsequence of a given array is an array generated by deleting some elements of the given array with the order of elements in the subsequence remaining the same as the order of elements in the array.

Note :
As this value might be large, print it modulo 10^9 + 7
Input format :
The first line contains an integer 'T' which denotes the number of test cases. Then the test cases follow :

The first line of each test case contains an integer 'N' representing the size of the array/list.

The second line contains 'N' single space - separated integers representing the elements of the array.
Output Format :
For each test case, print the total number of subsequences in which all elements are equal.

The output of each test case will be printed in a separate line.
Note :
You don't need to print anything. It has already been taken care of. Just implement the given function.
Constraints :
1 <= T <= 100
1 <= N <= 10^5
0 <= ARR[i] <= 10^9

Time Limit : 1 sec
Sample Input 1 :
2
1
5
2
1 0
Sample Output 1 :
1
2
Explanation For Sample Input 1 :
For the first query with input {5}, the total number of subsequences would be 2 which are {{""}, {5}}.
Out of these subsequences, there is only one subsequence which has all the same elements and that is {5} itself.

For the second query with input {1, 0}, the total number of subsequences would be 4 which are {{""}, {1}, {0}, {1, 0}}.
Out of these subsequences, there are two subsequences which have all the same elements and they are {1}, {0}.
Sample Input 2 :
2
2
1 1
3
1 1 1
Sample Output 2 :
3
7
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