# HackerRank ‘Pairs’ Solution

H
##### Short Problem Definition:

Given N integers, count the number of pairs of integers whose difference is K.

Pairs

##### Complexity:

time complexity is O(N*log(N))

space complexity is O(N)

##### Execution:

The solution is pretty straight-forward, just read the code :). The runtime complexity is calculated with log(N) access times for tree-based sets (not the case in Python).

##### Solution:
 1 2 3 4 5 6 7 8 9 10 11 12 13 #!/usr/bin/py def pairs(a,k):     answer = 0     s = set(a)     for v in s:         if v+k in s:             answer += 1           return answer if __name__ == '__main__':     n, k = map(int, raw_input().split())     b = map(int, raw_input().split())     print pairs(b, k)