Problem Statement

Given an array of unsorted numbers, find all unique triplets in it that add up to zero.

Examples

Example 1

• Input: [-3, 0, 1, 2, -1, 1, -2]
• Output: [[-3, 1, 2], [-2, 0, 2], [-2, 1, 1], [-1, 0, 1]]
• Explanation: There are four unique triplets whose sum is equal to zero.

Example 2

• Input: [-5, 2, -1, -2, 3]
• Output: [[-5, 2, 3], [-2, -1, 3]]
• Explanation: There are two unique triplets whose sum is equal to zero.

Constraints:

• 3 <= arr.length <= 3000
• -10⁵ <= arr[i] <= 10⁵