INVCNT  Inversion Count
Let A[0...n  1] be an array of n distinct positive integers. If i < j and A[i] > A[j] then the pair (i, j) is called an inversion of A. Given n and an array A your task is to find the number of inversions of A.
Input
The first line contains t, the number of testcases followed by a blank space. Each of the t tests start with a number n (n <= 200000). Then n + 1 lines follow. In the ith line a number A[i  1] is given (A[i  1] <= 10^7). The (n + 1)th line is a blank space.
Output
For every test output one line giving the number of inversions of A.
Example
Input: 2 3 3 1 2 5 2 3 8 6 1 Output: 2 5
hide comments
studyfather:
20170724 13:50:35
use merge sort and AC!!! 

ani_geek9654:
20170701 13:37:46
AC in 1


hzshang:
20170630 18:26:07
Binary tree, easy :P 

kartiks22:
20170626 09:40:03
took me 2 hours to figure out long long mistake !!! 

plab0n:
20170619 21:54:15
I am getting TLE in my merge_sort approach. Plz help me how can I make my code efficient.


lord_poseidon:
20170619 07:24:22
Easy one AC in one go


prodipdatta7:
20170612 18:05:30
AC in one go!!


abdrakhman:
20170602 09:48:56
AC in one go)))) 

anurag44:
20170525 04:38:39
Core concept of sorting algorithm.. 

thefriction:
20170502 14:53:24
thanks @fane_faiz :)

Added by:  Paranoid Android 
Date:  20100306 
Time limit:  3.599s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: PERL6 