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
kartikay singh:
20150618 18:56:34
after lots of TLEs


r0bo_dart:
20150613 13:35:15
HINT: Dont use vector for this problem with your custom designed insert. That will slow things out. Use array instead. Cost me 4 TLEs... phew. Else Merge Sort works nice. and yeah the long long thingy too. 

rudra21:
20150613 00:28:26
variation of Merge Sort algo.


ruler:
20150611 11:19:44
thanks @cr 

satyajit tourani:
20150611 08:18:34
easy after reading theory from CLRS( mergesort ) :) AC in 0.27 seconds. :D 

Akash Goel:
20150610 21:13:39
Couldn't AC without long long. Dunno why 

Nitesh Tiwari:
20150605 11:14:02
Reading these comments does help a lot.


Praveen Kulkarni:
20150603 15:59:39
my 50th 

hrwang_xn:
20150601 17:37:57
use BIT. 

scyth3r:
20150527 14:21:16
@I W G T J have you considered blank lines as input? 
Added by:  Paranoid Android 
Date:  20100306 
Time limit:  3.599s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: PERL6 