FourSum.java

import java.util.ArrayList;
import java.util.List;

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// Given an array nums of n integers and an integer target, are there elements a, b, c, and d in nums such that a + b + c + d = target? Find all unique quadruplets in the array which gives the sum of target.

// Note:

// The solution set must not contain duplicate quadruplets.

// Example:

// Given array nums = [1, 0, -1, 0, -2, 2], and target = 0.

// A solution set is:
// [
//   [-1,  0, 0, 1],
//   [-2, -1, 1, 2],
//   [-2,  0, 0, 2]
// ]


class Solution {
  public List<List<Integer>> fourSum(int[] nums, int target) {
      
  }
}