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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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2018-12-10 23:16:10
Used merge sort..Be careful to use long type instead of integer for count variable. Got wrong answer just for this mistake.. |
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2018-11-14 19:33:58
Fenwick Tree :: AC in one go :) |
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2018-10-30 11:05:02
solved using fenwick tree. ac in one go :) |
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2018-10-28 20:15:46
Use long in JAVA for storing the inversion-count to avoid WA |
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2018-10-10 16:22:44
beautiful use of merge_sort |
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2018-10-10 07:52:45
can anyone tell me constraints of test case T |
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2018-08-13 12:57:57
Use long to count inversions i got WA for using int in C++ |
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2018-08-12 15:42:54
AC in first go by Using BIT. Last edit: 2018-08-12 15:43:23 |
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2018-08-09 21:45:22
an application of merge sort.... ;) |
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2018-07-30 22:58:00
Policy-based data structures and AC |