3Sum
Difficulty: Medium
Category: DSA
Topics: Array, Two Pointers, Sorting
Asked at: Amazon, Facebook, Microsoft, Bloomberg, Apple, Adobe, VMware, Google, Cisco, Tesla, Goldman Sachs, eBay
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.
**Example 1:**
**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.
```
**Example 2:**
**Input:** nums = [0,1,1]
**Output:** []
**Explanation:** The only possible triplet does not sum up to 0.
```
**Example 3:**
**Input:** nums = [0,0,0]
**Output:** [[0,0,0]]
**Explanation:** The only possible triplet sums up to 0.
```
**Constraints:**
- `3 <= nums.length <= 3000`
- `-105 <= nums[i] <= 105`