# Pair Sum

Posted: 18 Feb, 2021
Difficulty: Easy

## PROBLEM STATEMENT

#### Note:

``````1. Pair (x,y) and Pair(y,x) are considered as the same pair.

2. If there exists no such pair with sum equals to 'TARGET', then return -1.
``````

#### Example:

``````Let ‘ARR’ = [1 2 3] and ‘TARGET’ = 4. Then, there exists only one pair in ‘ARR’ with a sum of 4 which is (1, 3). (1, 3) and (3, 1) are counted as only one pair.
``````
##### Input Format:
``````The first line of input contains an integer ‘T’ which denotes the number of test cases.

The first line of each test case contains two single space-separated integers ‘N’ and ‘TARGET’ representing the number of elements in the array/list ‘ARR’ and the required pair-sum respectively.

The next line of each test case contains ‘N’ single space-separated integers denoting the elements of  ‘ARR’.
``````
##### Output Format :
``````For each test case, return the numbers of pairs in  ‘ARR’ whose sum is equal to ‘TARGET’.
``````
##### Note:
``````You don't need to print anything, it has already been taken care of. Just implement the given function.
``````
##### Constraints:
``````1 <= ‘T’ <= 100
2 <= ‘N’ <= 5000
1 <= ‘ARR[i]’, ‘TARGET’ <= 10^5

Where ARR[i]’ represents the elements of array/list ‘ARR’.

Time Limit: 1 sec
``````