Even sum pairs
Given a list of integers, count the unordered pairs of positions (i, j) with i < j whose values sum to an even number. Two values sum to an even number exactly when they have the same parity. Aim for a solution that does not compare every pair directly. Example: [1, 2, 3, 4] has 2 such pairs: (1, 3) and (2, 4).
Implement
even_sum_pairs(nums: list[int]) → intExamples
in
[[1,2,3,4]]out2What a strong answer looks like
State your approach and its time/space complexity out loud before you optimize. Handle the edge cases (empty input, duplicates, overflow), and say why you chose this over the brute force. Green tests are the floor, not the grade.
0:00 of about 12 min
solution.py
InputExpectedGot
[[1,2,3,4]]2not run yetsample