Four-Sum to Target | Dataford Interview Questions

For a Pocket Gems game event, four reward values may combine to a required score. Given an integer array nums and an integer target, return every unique quadruplet [a, b, c, d] such that a + b + c + d == target.

Each quadruplet must be returned in nondecreasing order, and the complete result must not contain duplicate quadruplets. The same array element may be used only once in a quadruplet, although equal values at different indices may be selected. Return an empty list when no valid quadruplet exists. The order of quadruplets in the result does not matter.

Formal Specification

Input: nums, an array of integers, and target, an integer.
Output: A list of lists containing all unique value-based quadruplets whose sum equals target.

Constraints

1 <= nums.length <= 2000
-10^9 <= nums[i] <= 10^9
-10^9 <= target <= 10^9
Each array index may be used at most once
Quadruplets must be unique by values, not by indices

Function Signature

def four_sum(nums, target):

Your question is Four-Sum to Target. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem

Formal Specification

Input: nums, an array of integers, and target, an integer.
Output: A list of lists containing all unique value-based quadruplets whose sum equals target.

Constraints

1 <= nums.length <= 2000
-10^9 <= nums[i] <= 10^9
-10^9 <= target <= 10^9
Each array index may be used at most once
Quadruplets must be unique by values, not by indices

Function Signature

def four_sum(nums, target):

Your question is Four-Sum to Target. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.