FREQUENT - Frequent values

You are given a sequence of n integers a1, a2 ... an in non-decreasing order. In addition to that, you are given several queries consisting of indices i and j (1 ≤ i ≤ j ≤ n). For each query, determine the most frequent value among the integers ai ... aj.

Input Specification

The input consists of several test cases. Each test case starts with a line containing two integers n and q (1 ≤ n, q ≤ 100000). The next line contains n integers a1 ... an (-100000 ≤ ai ≤ 100000, for each i ∈ {1 ... n}) separated by spaces. You can assume that for each i ∈ {1 ... n-1}: ai ≤ ai+1. The following q lines contain one query each, consisting of two integers i and j (1 ≤ i ≤ j ≤ n), which indicate the boundary indices for the query.

The last test case is followed by a line containing a single 0.

Output Specification

For each query, print one line with one integer: The number of occurrences of the most frequent value within the given range.

Sample Input

10 3
-1 -1 1 1 1 1 3 10 10 10
2 3
1 10
5 10
0

Sample Output

1
4
3

A naive algorithm may not run in time!

Added by:Adrian Kuegel
Date:2007-07-06
Time limit:1s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All except: ERL JS-RHINO NODEJS PERL6 VB.NET
Resource:University of Ulm Local Contest 2007

hide comments
2016-09-13 16:04:51 shubham
AC in one go... concept similar to http://www.spoj.com/problems/GSS1/
using prefix sum and suffix sum..
2016-08-29 14:19:02
Attention : The input consists of several test cases ! :-)
2016-08-19 11:00:32 hashem sllat
is there any approach to solve this problem in O(n*log(n) ) when array is not sorted ?
2016-08-17 21:29:59 kumar gaurav
getting TLE, even if O(n) for preprocessing and O(log n) for each queries.
2016-07-25 16:24:03 Shrish Lal Bhatnagar
AC in O(n) preprocessing and O( log (n) ) for each query
2016-07-06 06:39:24
memory problem :(
RUN time error..:'(
now TLE..:O

Last edit: 2016-07-06 07:06:46
2016-06-02 19:04:31
Well You can also use MO's algorithm with either O(N*sqrt(N) ) or O(N*sqrt(N)*log(N)) algorithm :p
2016-01-14 10:34:44 minhthai
tle in java :(
2015-12-25 06:44:56 anshal dwivedi
Yo! AC in one go....! XD
2015-11-25 21:10:26
there are quite a few cases which should be taken care of while merging, this is the most important step in this problem
© Spoj.com. All Rights Reserved. Spoj uses Sphere Engine™ © by Sphere Research Labs.