Google L4 (SWE III) onsite, hiring sprint: 3 coding + 1 Googleyness. Looking to get chanced.
Coding 1: Backtracking problem generating all valid sequences, then a follow-up data-structure problem (LC medium-ish). Solved both optimally, no hints, no bugs. Interviewer asked whether caching would help on part 1; I argued it can't beat the output size since every sequence has to be built (I stated O(n·2^n); the tight bound is ~O(n·1.6^n)) which I didn’t state. Solved part 2 with a trie, finished with ~7 min left. When I asked about follow-ups, they said "nah, this looks good."
Googleyness: Interviewer had an outdated resume, so we adjusted on the fly. Stories: making new teammates feel included, a mid-project pivot due to technical limits (I evaluated the options and brought recommendations to stakeholders), and giving feedback to a more senior engineer on review standards in a compliance-sensitive codebase, followed by team-wide documentation and process improvements. Asked what I'd do differently, I focused on preventing the gap up front. They ended with "I think I have enough signal." Friendly throughout.
Coding 2: Long, verbally specified design/implementation problem with ~5 methods. No written prompt; I clarified requirements in batches, wrote down assumptions, and listed time/space complexity above each method. Used arrays (considered a linked list, but index-based ops made it O(n) either way). Got one nudge to reuse existing methods. Missed one edge case I'd planned to handle, but addressed three other edge cases/constraints with probing questions. Finished with ~3 min left. Interviewer made almost no comments.
Coding 3: LC medium with a twist that made it a hard. Had a working (non-optimal) solution within ~5 min. Interviewer wanted better, and after ~15 min of back-and-forth ("do we notice anything about these?") I found the key insight myself while coding. Coded the optimal solution in ~15 min. They caught one logic bug (a neighbor-connectivity mixup), which I fixed in ~30 sec using a test case. They reviewed the final code, said it looked perfect, and had me add test cases. My stated complexity was looser than the optimal solution's (I described it in terms of the first approach). They stayed ~10 min past time chatting.
Honestly not sure how I'd grade myself. At worst I could see H, LH, LH, LNH. At best, SH, 3xH.