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)]
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