Given an array of integers nums and an integer target, find all unique quadruplets [a, b, c, d] such that a + b + c + d = target.
nums = array of integers, target = integer
List of quadruplets that sum to target
Example 1:
Input:
nums = [1,0,-1,0,-2,2] target = 0
Output:
[[-2,-1,1,2],[-2,0,0,2],[-1,0,0,1]]
Explanation:
Three unique quadruplets sum to 0.