93. 4Sum

Given an integer array nums and an integer target, return all unique quadruplets [a,b,c,d] such that a+b+c+d == target. No duplicate quadruplets.

Input: Integer array nums and integer target.

Output: List of unique quadruplets summing to target.

Examples

Example 1

Input: [1,0,-1,0,-2,2],0
Output: [[-2,-1,1,2],[-2,0,0,2],[-1,0,0,1]]
Explanation: All quadruplets summing to 0.

Example 2

Input: [2,2,2,2,2],8
Output: [[2,2,2,2]]
Explanation: Only one unique quadruplet.

Example 3

Input: [1,2,3,4],0
Output: []
Explanation: No quadruplet sums to 0.