Count Pairs Problem Statement

You are given an array A of length N consisting only of integers. Additionally, you are provided with three integers X, Y and SUM. Your task is to count the number of pairs (i, j) where i < j such that (A[i] * X + A[j] * Y) == SUM.

Input:

The input starts with an integer T, representing the number of test cases. Each test case consists of:

1. A single line containing four integers: N, X, Y, SUM
   where N is the size of the array, X and Y are multipliers, and SUM is the target sum.
2. The next line contains N space-separated integers that make up the array A.

Output:

For each test case, output a single integer that denotes the number of pairs (i, j) where (A[i]*X + A[j]*Y) == SUM.
Output each result on a new line.

Example:

Input:

N = 3, A = {3, 1, 2, 3}, X = 4, Y = 2, SUM = 14

Output:

2

Explanation:

The possible valid pairs based on the condition are (1, 3) and (3,4) as they both satisfy the equation.

Constraints:

• 1 <= T <= 10
• 1 <= N <= 105
• 1 <= X, Y <= 104
• 1 <= SUM <= 109
• 0 <= A[i] <= 105

It is guaranteed that the count of pairs will fit in a 32-bit integer.

The sum of N across all test cases is <= 10⁵.

Time limit: 1 second.