HACKRNDM - Hacking the random number generator

You recently wrote a random number generator code for a web application and now you notice that some cracker has cracked it. It now gives numbers at a difference of some given value k more predominantly. You being a hacker decide to write a code that will take in n numbers as input and a value k and find the total number of pairs of numbers whose absolute difference is equal to k, in order to assist you in your random number generator testing.

NOTE: All values fit in the range of a signed integer, n, k>=1


1st line contains n & k.
2nd line contains n numbers of the set. All the n numbers are assured to be distinct.

(Edited: n <= 10^5)


One integer saying the no of pairs of numbers that have a diff k.


5 2
1 5 3 4 2 Output: 3

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rc_alex36: 2015-12-08 12:49:20

0.04s using the two pointers method. Even faster than binary search as the time complexity is only O(n) instead of O(nlogn).

Last edit: 2015-12-08 12:50:42
Prateek Agarwal: 2015-11-28 14:18:39

binary search 0.04s 3.7M
STL 0.11s 9M

danish_shark: 2015-11-04 11:35:00

worked in 0.26 secs. O(n) using java.util.HashMap :)

hodobox: 2015-08-25 17:59:32

venkatesh, you have to check for element-k as well

ASHUTOSH DWIVEDI: 2015-08-17 23:51:47

quick sort + binary search ==> AC..

venkatesh: 2015-08-06 05:37:46

I am getting WA in python. Can someone tell me, what is wrong?
I am using sets for checking element + k is exist or not?

Last edit: 2015-08-06 05:49:08
venkatesh: 2015-08-05 08:18:07

set is good

hrishabh: 2015-08-02 20:51:14

binary search..;)

Vaporeon: 2015-07-27 19:52:08

easy :)

Anurag Sharma: 2015-07-25 19:05:58

Merge sort + binary search =AC in one go...... should be considered as tutorial problem.... only for dummies :P

Added by:vijay
Time limit:1s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All except: ASM64
Resource:Own Problem