Problem of the day
A pair ('ARR[i]', 'ARR[j]') is said to be an inversion when:
1. 'ARR[i] > 'ARR[j]'
2. 'i' < 'j'
Where 'i' and 'j' denote the indices ranging from [0, 'N').
The first line of input contains an integer 'N', denoting the size of the array.
The second line of input contains 'N' integers separated by a single space, denoting the elements of the array 'ARR'.
Print a single line containing a single integer that denotes the total count of inversions in the input array.
You are not required to print anything, it has been already taken care of. Just implement the given function.
1 <= N <= 10^5
1 <= ARR[i] <= 10^9
Where 'ARR[i]' denotes the array element at 'ith' index.
Time Limit: 1 sec
3
3 2 1
3
We have a total of 3 pairs which satisfy the condition of inversion. (3, 2), (2, 1) and (3, 1).
5
2 5 1 3 4
4
We have a total of 4 pairs which satisfy the condition of inversion. (2, 1), (5, 1), (5, 3) and (5, 4).