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] ≤ 107). 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
MAYANK NARULA:
2015-07-12 23:16:54
Aah well somethings never change! Just don't forget to use long long..
|
|
rini22:
2015-07-11 16:29:13
use long long |
|
chin:
2015-07-02 10:53:20
AC in 2nd attempt!!....A very good application of Mergesort!! |
|
mohit:
2015-06-28 18:32:31
mergesort .. AC after 4 WA!!! give special attention to type... |
|
THECOLDONE:
2015-06-24 14:14:31
after reading BIT done it by merge algo
|
|
Aditya Kumar:
2015-06-24 09:18:21
Be careful with overflows
|
|
Sahil:
2015-06-20 15:42:51
You only need the inversion count in long long (guess why? look at the worst case for this problem).
|
|
[Mayank Pratap]:
2015-06-20 05:22:08
After months finally AC :) |
|
kartikay singh:
2015-06-18 18:56:34
after lots of TLEs
|
|
r0bo_dart:
2015-06-13 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. |
Added by: | Paranoid Android |
Date: | 2010-03-06 |
Time limit: | 3.599s |
Source limit: | 50000B |
Memory limit: | 1536MB |
Cluster: | Cube (Intel G860) |
Languages: | All except: PERL6 |