DSA problem
4Sum
Given an array nums of n integers, return an array of all the unique quadruplets [nums[a], nums[b], nums[c], nums[d]] such that:
0 <= a, b, c, d < na,b,c, anddare distinct.nums[a] + nums[b] + nums[c] + nums[d] == target
You may return the answer in any order. The solution set must not contain duplicate quadruplets, where two quadruplets are duplicates if they consist of the same four values regardless of order.
Examples
Example 1
Input:
nums = [1,0,-1,0,-2,2], target = 0Output:
[[-2,-1,1,2],[-2,0,0,2],[-1,0,0,1]]Explanation: These are the three distinct quadruplets whose values sum to the target 0.
Example 2
Input:
nums = [2,2,2,2,2], target = 8Output:
[[2,2,2,2]]Explanation: The only quadruplet is [2,2,2,2]. Value-based deduplication yields a single unique quadruplet.
Constraints
- 1 <= nums.length <= 200
- -10^9 <= nums[i] <= 10^9
- -10^9 <= target <= 10^9
3 hints and a full solution walkthrough with step-by-step visualizations are available in the practice editor.