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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
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 |
hide comments
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2015-06-13 00:28:26
variation of Merge Sort algo. output type is long long. Thank You @ankur manchanda @Nitesh Tiwari |
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2015-06-11 11:19:44 ruler
thanks @cr |
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2015-06-11 08:18:34 satyajit tourani
easy after reading theory from CLRS( mergesort ) :) AC in 0.27 seconds. :D |
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2015-06-10 21:13:39 Akash Goel
Couldn't AC without long long. Dunno why |
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2015-06-05 11:14:02 Nitesh Tiwari
Reading these comments does help a lot. Make sure to declare a proper count variable, other all can be fit into int. Question is just a standard variation of merge sort. |
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2015-06-03 15:59:39 Praveen Kulkarni
my 50th |
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2015-06-01 17:37:57 hrwang_xn
use BIT. |
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2015-05-27 14:21:16 scyth3r
@I W G T J have you considered blank lines as input? |
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2015-05-27 09:59:18 I W G T J
Why WA? <snip> can anyone please help? Last edit: 2022-06-26 16:04:47 |
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2015-05-26 19:42:48 scyth3r
tough for python....challenge for pythonistas :D:D Last edit: 2015-05-26 19:44:43 |