Description
Solutions
Get Discount Pairs 🍊
🔥 FULLTIME

Amazon is offering a discount on every purchase of a pair of products whose price sum is divisible by x. Given the price of n products in the store, find the number of pairs (i, j) where i < j and prices[i] + prices[j] is divisible by x.

Function Description

Complete the function getDiscountPairs in the editor.

getDiscountPairs has the following parameter(s):

  1. 1. int x: sum of a pair of integers should be divisible by this number
  2. 2. int prices[n]: the prices of the products

Returns

int: the number of pairs in the array whose sum is divisible by x

Example 1: 

Input:  x = 60, prices = [31, 25, 85, 29, 35]
Output: 3 
Explanation:

The answer is 3 based on the pairs (31, 29), (25, 35), and (85, 35). Each pair sums to a number divisible by x.
Constraints:

    1 ≤ x ≤ 2 * 109

    1 ≤ n ≤ 105

    1 ≤ prices[i] ≤ 9

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Testcase
Result
Case 1

input:

output: