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SWAPS - Counting inversions |
You are given a sequence A of N (N≤250000) integers between 1 and 50000. On this sequence you have to apply M (M≤10000) operations of the form: modify the i-th element in the sequence and then say how many inversions are there in the sequence. The number of inversions in a sequence is given by the number of pairs (i, j) with i < j and Ai > Aj.
Input
The first line of input contains the number N and the next line contains the numbers that form the sequence. After that follows the number M and then M lines, each containing 2 integers X and Y, meaning that new value of the X-th element of the sequence is Y and that you should count the number of inversions in the modified sequence.
Output
Output must contain M lines, the i-th line of output containing the number of inversions in the sequence after the first i operations.
Example
Input: 10 2 6 6 4 7 6 3 5 9 1 7 8 8 5 1 5 6 10 5 7 1 10 10 4 6 Output: 17 18 16 13 14 8 6
Added by: | Gogu |
Date: | 2006-05-31 |
Time limit: | 1s |
Source limit: | 50000B |
Memory limit: | 1536MB |
Cluster: | Cube (Intel G860) |
Languages: | All except: ERL JS-RHINO NODEJS PERL6 VB.NET |
Resource: |
hide comments
2019-07-13 21:21:54
@Aman Shrivastava->> integers between 1 and 50000 |
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2017-06-21 16:37:29
Solved in one go ... works O(n^2) code :') |
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2017-05-01 09:32:30
Using segment wiht each node a BIT -> N(log(N)^2) + Q(log(N)^2) -> TLE N(log(N)) + Q(log(N)^2) -> AC So Nice and like it Last edit: 2017-05-03 15:14:26 |
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2017-03-16 01:07:24 Dipjal
At single go! :D |
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2015-05-02 16:55:32
Solved using sqrt(n) - length sequence preprocessing and fast read ^_^! Even though my complexity was (I think) worse than it should have been ( O( sqrt(n) * log(50000) ) per query ), it seemed to go rather well in practice (0.96 on time). Is there a solution in O(log(n)) per query? Last edit: 2015-05-02 16:56:10 |
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2015-01-12 21:05:14 Naman Taneja
Nice Question ! A little optimization is required Last edit: 2015-01-14 21:26:59 |
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2014-09-14 14:42:42 Archit Jain
segment tree giving tle? Help |
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2014-09-13 06:19:18 Aman Shrivastava
limits of Ai??? Last edit: 2014-09-13 06:19:31 |