15. 3Sum

Example1

Input: nums = [-1,0,1,2,-1,-4]
Output: [[-1,-1,2],[-1,0,1]]
Explanation: 
nums[0] + nums[1] + nums[2] = (-1) + 0 + 1 = 0.
nums[1] + nums[2] + nums[4] = 0 + 1 + (-1) = 0.
nums[0] + nums[3] + nums[4] = (-1) + 2 + (-1) = 0.
The distinct triplets are [-1,0,1] and [-1,-1,2].
Notice that the order of the output and the order of the triplets does not matter.

Example2

Input: nums = [0,1,1]
Output: []
Explanation: The only possible triplet does not sum up to 0.

조건

3 <= nums.length <= 3000
-105 <= nums[i] <= 105

class Solution:
    def threeSum(self, nums: List[int]) -> List[List[int]]:
        nums.sort()
        s = set()
        for k, v in enumerate(nums):
            l, r = k+1, len(nums)-1
            print(k, v, l, r)
            while l < r:
                sums = v + nums[l] + nums[r]
                if sums == 0:
                    s.add((v, nums[l], nums[r]))
                    if nums[l] == nums[r]:
                        break
                    l += 1
                    r -= 1
                elif sums > 0:
                    r -= 1
                elif sums < 0:
                    l += 1
        return list(s)