4Sum

You are given an integer array nums of size n, return an array of all the unique quadruplets [nums[a], nums[b], nums[c], nums[d]] such that:

• 0 <= a, b, c, d < n
• a, b, c, and d are distinct.
• nums[a] + nums[b] + nums[c] + nums[d] == target

You may return the answer in any order.

Note: [1,0,3,2] and [3,0,1,2] are considered as same quadruplets.

Example 1:

Input: nums = [3,2,3,-3,1,0], target = 3

Output: [[-3,0,3,3],[-3,1,2,3]]

Example 2:

Input: nums = [1,-1,1,-1,1,-1], target = 2

Output: [[-1,1,1,1]]

Constraints:

• 1 <= nums.length <= 200
• -1,000,000,000 <= nums[i] <= 1,000,000,000
• -1,000,000,000 <= target <= 1,000,000,000