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MKTHNUM - K-th Number |
English | Vietnamese |
You are working for Macrohard company in data structures department. After failing your previous task about key insertion you were asked to write a new data structure that would be able to return quickly k-th order statistics in the array segment.
That is, given an array a[1 ... n] of different integer numbers, your program must answer a series of questions Q(i, j, k) in the form: "What would be the k-th number in a[i ... j] segment, if this segment was sorted?"
For example, consider the array a = (1, 5, 2, 6, 3, 7, 4). Let the question be Q(2, 5, 3). The segment a[2 ... 5] is (5, 2, 6, 3). If we sort this segment, we get (2, 3, 5, 6), the third number is 5, and therefore the answer to the question is 5.
Input
The first line of the input contains n — the size of the array, and m — the number of questions to answer (1 ≤ n ≤ 100000, 1 ≤ m ≤ 5000).
The second line contains n different integer numbers not exceeding 10^9 by their absolute values — the array for which the answers should be given.
The following m lines contain question descriptions, each description consists of three numbers: i, j, and k (1 ≤ i ≤ j ≤ n, 1 ≤ k ≤ j - i + 1) and represents the question Q(i, j, k).
Output
For each question output the answer to it — the k-th number in sorted a[i ... j] segment.
Example
Input: 7 3 1 5 2 6 3 7 4 2 5 3 4 4 1 1 7 3 Output: 5 6 3
Note: a naive solution will not work!!!
Added by: | psetter |
Date: | 2009-02-24 |
Time limit: | 1s |
Source limit: | 50000B |
Memory limit: | 1536MB |
Cluster: | Cube (Intel G860) |
Languages: | All except: ERL JS-RHINO |
Resource: | Northeastern Europe 2004 Northern Subregion |
hide comments
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2016-07-16 11:01:50 akshayv3
Solved using Persistent Segment trees and execution time was 0.5 s and the same solution times out in c++ 4.3.2 |
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2016-06-24 21:10:51
binary search +persistence segment tree.. binary search over -10^9 to +10^9 got tle.. binary search over elements of arr got ac.. log(2*10^9) factor proved very costly than log(10^5)... :-) |
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2016-01-01 19:01:50
@anando_du same thing happened to me , your comment was helpful |
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2015-10-18 20:39:53 Abhinandan Agarwal
N(log N)+M(log N)**3 solution gives TLE .. :-\ |
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2015-09-29 19:14:58 Sudharsansai
Learnt a lot . Merge Sort Tree : O((N+M)*lgN*lgN) Persistent Segment Tree : O((N+M)*lgN) |
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2015-09-26 04:15:28 Shahed Shahriar
in c++(g++4.3.2) got WA and with the same code got AC in c++14 (g++5.1) |
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2015-09-01 08:52:34 Pulkit Singhal
Persistent Segment Tree Nailed It :D |
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2015-07-22 12:05:51 anando_du
used scanf() printf() got AC .. used getchar_unlocked() , putchar_unlocked() got wa O.o btw nice one ! |
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2015-07-03 16:29:21 ankit kumar
!micro !soft=macro hard; hahaha nyc.. problem indeed!! |
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2015-06-10 16:56:38 i_am_looser
persistent segment tree. Got AC using O(nlog(n)) ; ) |