15. 3Sum - LeetCode

class Solution:
    def threeSum(self, nums: list[int]):
        result = set()
        zero, neg, pos = counters = {}, {}, {}
        for num in nums:
            counter = counters[(num > 0) + (num != 0)]
            counter[num] = counter.get(num, 0) + 1
        # 0,0,0
        if zero.get(0, 0) >= 3:
            result.add((0, 0, 0))
        # -,+,?
        for n in neg:
            for p in pos:
                target: int = -(n + p)
                counter = counters[(target > 0) + (target != 0)]
                if target in counter:
                    triplet = tuple(sorted([n, p, target]))
                    if target in (n, p):  # duplicate
                        if counter[target] >= 2:
                            result.add(triplet)
                    else:
                        result.add(triplet)
        return result