Three Sum Problem

Write a function that returns all sets of three elements that sum to 0.

Examples

threeSum([0, 1, -1, -1, 2]) ➞ [[0, 1, -1], [-1, -1, 2]]

threeSum([0, 0, 0, 5, -5]) ➞ [[0, 0, 0], [0, 5, -5]]

threeSum([1, 2, 3]) ➞ []

threeSum([1]) ➞ []

Notes

• The original array may contain duplicate numbers.
• Each three-element subarray in your output should be distinct.
• Subarrays should be ordered by the first element of the subarray.
• Subarrays themselves should be ordered the same as the original array.
• Return an empty array if no three elements sum to zero.
• Return an empty array if there are fewer than three elements.