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
carofe82:
2024-08-07 17:00:39
I got AC with golang. As others have said, make sure you use int64 for the result count. |
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hs1800002:
2024-06-05 02:22:35
<snip>
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pudo1234:
2024-03-25 09:20:56
@onis No you use your brain so I don't think you can solve it
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onis:
2024-03-25 09:20:05
guys do I use the amogus method to solve this????? |
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pratyushgadge1:
2023-10-13 20:41:33
i agree with @hraj123. don't use int. i used long long and got my solution accepted in the first try after the update; |
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orgil0127:
2023-06-27 06:57:03
HELLO world <2
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hraj123:
2023-06-10 12:28:50
@new_mutant, it will overflow bcoz of array size not bcoz of array values, as total pair values can have upperbound as (n^2-n)/2 where n<=2e5. Last edit: 2023-06-27 19:31:46 |
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leonardodpv:
2023-05-08 02:10:41
Ojo con el numero de "inversions" que se pueden dar en casos muy grandes y ordenados. Last edit: 2023-05-08 02:11:02 |
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mddinislam:
2023-05-04 14:06:55
How the first test case answer is 2 ? |
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cprakash123:
2023-03-27 18:57:36
solving first time ........... |
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 |