Count Inversions Problem Statement

Given an integer array ARR of size N, your task is to find the total number of inversions that exist in the array.

An inversion is defined for a pair of integers in the array when both of the following conditions are met:

• ARR[i] > ARR[j]
• i < j

Here, i and j are indices ranging from 0 to N-1.

Example:

Input:

N = 5
ARR = [2, 4, 1, 3, 5]

Output:

3

Explanation:

The inversions are: (2, 1), (4, 1), (4, 3), and hence the output is 3.

Constraints:

• 1 <= N <= 10^5
• 1 <= ARR[i] <= 10^9
• Time Limit: 1 sec

Note:

You are not required to print anything; it has been taken care of. Just implement the function to return the result.