https://leetcode.com/problems/3sum

gistfile1.py

from collections import defaultdict

class Solution:
    def threeSum(self, nums: List[int]) -> List[List[int]]:
        nums_count_map = defaultdict(int)
        result_set = set()
        for n in nums:
            nums_count_map[n] += 1
        for n in nums_count_map:
            for m in nums_count_map:
                if n == m and nums_count_map[n] < 2:
                    continue
                target = 0 - m - n
                if target in nums_count_map:
                    if target == n == m and nums_count_map[target] < 3:
                        continue
                    if (target == n or target == m) and nums_count_map[target] < 2:
                        continue
                    result_set.add( tuple(sorted([target, n, m])) )
        return result_set