Given an integer array nums, return all the triplets
[nums[i], nums[j], nums[k]] such that
i != j,
i != k, and
j != k, and
nums[i] + nums[j] + nums[k] == 0.
Notice that the solution set must not contain duplicate triplets.
[-1, 0, 1, 2, -1, -4]
[[-1, -1, 2], [-1, 0, 1]]
[0, 1, 1]
[]
[0, 0, 0]
[[0, 0, 0]]