Sig's coding rounds are generally considered medium to hard difficulty, similar to Google and Meta. The key difference is Sig's strong emphasis on clean, production-quality code and thorough communication of your thought process, not just reaching a solution. Expect problems that test algorithmic depth (often graphs, DP, or complex data structures) and require handling edge cases explicitly.

Mastering Sig's 16 Leadership Principles (LPs) is non-negotiable and often the deciding factor. While DSA is critical, you must prepare structured, specific stories from your past experience that demonstrate these LPs (e.g., 'Customer Obsession,' 'Invent and Simplify'). Practice articulating these stories using the STAR method and be ready to discuss how you applied them in technical scenarios.

Aim for a minimum of 150-200 high-quality problems, with a heavy focus on medium and hard difficulty. Prioritize problems tagged with 'Sig' on LeetCode to understand their specific style, and ensure you can solve problems across all core patterns (arrays, strings, graphs, trees, DP, design). More important than quantity is the ability to solve any new problem by mapping it to a known pattern.

The biggest mistake is treating the Bar Raiser as a standard behavioral interview. It's a deep dive into your leadership experience and judgment. Candidates often provide vague answers without concrete metrics or fail to connect their past decisions to Sig's LPs. Prepare detailed stories about challenging projects, conflicts, and failures, emphasizing your specific role, the trade-offs you considered, and the measurable outcome.

The Bar Raiser is an interview with a senior leader from a different team who evaluates you against a higher hiring bar to maintain quality across Sig. It extensively probes your leadership principles, decision-making, and ability to handle ambiguity. Prepare by deeply reviewing your project history, identifying 5-7 robust stories that cover multiple LPs, and practice discussing technical trade-offs at an architectural level, even for non-architect roles.

The process typically takes 4-8 weeks. After an initial recruiter screen (1 week), you'll have a 45-60 minute virtual technical assessment (1-2 weeks later). If successful, you move to the full onsite loop (4-5 interviews over 1-2 weeks). Final team matching and offer deliberation can take 1-3 weeks. Delays often occur in the team-matching phase, so patience is key. Always follow up with your recruiter for status updates.

SDE-1 (new grad) focuses intensely on DSA fundamentals and basic LP understanding. SDE-2 expects strong problem-solving plus demonstrable impact on past projects (scope, ownership). SDE-3 adds a significant system design component (high-level, scalable architectures) and requires deep, multi-faceted leadership examples (influencing without authority, mentoring, strategic impact). The Bar Raiser intensity increases with level.

Use the 'Sig' tag on LeetCode for relevant problems. Thoroughly study the 'Leadership Principles' page on Sig's career site and find official examples. Read 'Sig's Approach to System Design' documents (often shared by recruiters). Practice mock interviews with a focus on vocalizing your thought process. Finally, research recent Sig engineering blog posts to understand current tech stack and challenges for the team you're targeting.