Target Sum and Memoization | Dataford Interview Questions

Explain how you would solve the problem of finding two numbers in an array that sum to a target, and how you would use memoization to improve it.

Implement two_sum(nums, target), which returns the indices of two distinct elements whose values sum to target, or an empty array if no pair exists. Explain why caching previously seen values avoids repeated pair checks.

Assume the array contains at least two integers. Values and the target may be negative, and each element may be used only once.

Constraints

2 <= nums.length <= 10^4
-10^9 <= nums[i] <= 10^9
-10^9 <= target <= 10^9
Each element may be used at most once
There may be zero or one valid pair

Function Signature

def two_sum(nums, target):

Your question is Target Sum and Memoization. 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

Explain how you would solve the problem of finding two numbers in an array that sum to a target, and how you would use memoization to improve it.

Assume the array contains at least two integers. Values and the target may be negative, and each element may be used only once.

Constraints

2 <= nums.length <= 10^4
-10^9 <= nums[i] <= 10^9
-10^9 <= target <= 10^9
Each element may be used at most once
There may be zero or one valid pair

Function Signature

def two_sum(nums, target):

Your question is Target Sum and Memoization. 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.