Software Engineer

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

You are given an integer array 'ARR' of size 'N' and an integer 'S'. Your task is to return the list of all pairs of elements such that each sum of elements of each pair equals 'S'.

Note:

Each pair should be sorted i.e the first value should be less than or equals to the second value. 

Return the list of pairs sorted in non-decreasing order of their first value. In case if two pairs have the same first value, the pair with a smaller second value should come first.