Loading…
Combination Sum is a medium coding interview question covering backtracking, recursion, arrays — the kind asked at FAANG (Facebook/Meta, Apple, Amazon, Netflix, Google) and AI-first companies like Anthropic, OpenAI, and Nvidia.
Given an array of distinct positive integers and a target, return all unique combinations that sum to the target. The same number may be chosen an unlimited number of times. Example: candidates = [2,3,6,7], target = 7 -> [[2,2,3],[7]].
Solution walkthrough on Pro
Upgrade to Pro to unlock the guided hints, the step-by-step walkthrough, solutions in Python, C++, Java, and Go, and complexity analysis.
What's inside this guide
Fully unlocked, no account needed — solutions, walkthroughs and follow-up answers included.
Or start the Study Plan — a week-by-week order for your loop, and week 1 is entirely free.
A full interview loop is more than one round. These are the others, each with what is on the site for it.