Given a list of integers and a positive integer k, write a Python program to count all distinct pairs with difference equal to k.
Input : [1, 5, 3, 4, 2], k = 3 Output : [(5, 2), (4, 1)] Input : [8, 12, 16, 4, 0, 20], k = 4 Output : [(8, 4), (12, 8), (16, 12), (4, 0), (20, 16)]
Approach #1 : Python list comprehension
We will use list comprehension using two loops using ‘e1’ and ‘e2’ that will traverse given list. We check if e1-e2 == k or not and return the (e1, e2) tuple respectively. Finally, a list with required tuples will be returned.
[(5, 2), (4, 1)]
Approach #2 :
This is an efficient approach with respect to the above approach as it uses only O(n) space. We take an empty list to store the output. Then, we use a loop with iterator ‘e’ to traverse through given list. In every iteration, we check is e+k i.e the required pair integer for e is available or not. If yes, we append the tuple to ‘res’.
[(1, 4), (2, 5)]
Approach #3 :
The best approach is to use the inbuilt function from itertools module. combinations() produces an iterator over tuples of all combinations of n elements in inputs. We make the use of these combinations and output those having ‘k’ difference.
[(1, 4), (5, 2)]
Attention geek! Strengthen your foundations with the Python Programming Foundation Course and learn the basics.
To begin with, your interview preparations Enhance your Data Structures concepts with the Python DS Course.