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Go step by step: try it yourself before the video and the visual. Progress saves on this device.
Community-reported · source · updated 2026-10-08. ● asked in the last 6 months.
Step 1
Know these before you start
Tick what you already know
Step 2
Try it on paper
5–10 minutes, no code yet
Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target.
You may assume that each input would have exactly one solution, and you may not use the same element twice. You can return the answer in any order.
Step 6
Get it accepted
All test cases pass
Step 7
Review it so it sticks
Re-solve from memory after
Reading the solution first feels like progress, but it makes the next similar problem — and the interview version — much harder, because you skipped the part where you figure it out. Give it an honest 20–30 minutes. Stuck? Re-read the pattern, watch the concept video, or try the brute force first.
Hidden: approach · solution code · optimal solution