I know there are a few older threads on AT&T's coding interview but most of them are from 2022-2023 and I'm not sure how much has changed, so here's a current (early 2026) account.
I applied for a SWE role on their corporate IT/applications side. The recruiter said after the phone screen I'd get a HackerRank assessment link and I had 7 days to complete it (but had to finish once I started).
Format: 90 minute timer 3 problems Mix of coding and one data/SQL section
The problems I got:
Problem 1: String manipulation. Find the longest palindromic substring. Classic medium, nothing tricky.
Problem 2: Binary tree traversal variant. They gave a tree and asked me to find the right side view (nodes visible when looking from the right). Also medium.
Problem 3: SQL. Multiple tables, asked to find customers who purchased in every quarter of a year. Window function or grouping approach. This one took me the longest.
Time: I finished in about 75 minutes. Didn't feel rushed.
Language: I used Python. Not sure if any language is preferred. No one told me to use Java specifically.
Difficulty calibration: This is not FAANG-level hard. If you've done 50-80 LeetCode mediums and have basic SQL down, you should be comfortable. I didn't see anything that required a complex data structure like a segment tree or advanced graph algorithm.
One thing I noticed: They're using HackerRank's standard interface (not a custom platform), so if you've done HackerRank practice problems before, the UX is familiar.
After the OA, I waited about 10 days before hearing back. They said they'd review within a week but it slipped. Just something to be aware of. AT&T's recruiting timeline is a bit loose.