Jane Street interview leak surfaces

Jane Street’s software-engineering mock interview resurfaced on Wednesday after a social-media post drew attention to a video showing a live coding session built around unit conversion. The clip itself is not a newly leaked internal recording. Jane Street hosts the video on its own website as a published mock interview using what the firm calls a “now retired interview question.” The company page lists the video at 37 minutes and 24 seconds and says two Jane Street software engineers, Grace and Nolen, walk through “a typical Jane Street software engineering interview.” The timeline on the page shows the interview beginning at 00:48, coding starting at 10:32, and a closing section on what the firm looks for in interviews beginning at 34:10. ### Was this actually a leak? (janestreet.com) Jane Street says on its mock-interview page that it is “sharing a recording of a mock interview” to help candidates understand the process. The page says the problem in the video is retired, and that the engineers discuss “how to communicate with your interviewer, how we think about code quality, and how to practice.” A separate Jane Street interview page says the firm wants its processes to be transparent and that “much of the information floating around on the internet is outdated or wrong.” That page frames the published materials as an effort to show applicants what to expect rather than as an accidental disclosure. (janestreet.com) ### What problem does the mock interview use? Jane Street’s mock interview uses a unit-conversion coding problem in which conversions may require multiple hops between known relationships, according to the company’s video page and third-party writeups of the same mock interview problem. (janestreet.com) A GitHub repository describing a solution says the task involves facts such as meters to feet and hours to minutes, with no guarantee a conversion path exists. (janestreet.com) Third-party explanations of the mock interview describe the problem as a graph search over conversion relationships. That matches the social-media description of the task as a breadth-first-search-style unit-conversion exercise, though Jane Street’s own page does not label it BFS in the excerpt surfaced by search. ### What does Jane Street say it evaluates? Jane Street’s mock-interview page highlights three closing advice sections: “Communication,” “Clear and correct code,” and “Practice.” The company tells candidates to “talk through your ideas out loud” and to write out all parts of the problem when practicing. (janestreet.com) Its software-engineering interview guide says candidates are expected to write code in a real programming language and that “the journey through the interview is a lot more important than the snapshot of the solution at the end of it.” The same page says Jane Street prefers open-ended problems with several plausible approaches, rather than “algorithm bingo” or puzzles with a single clever trick. (github.com) (janestreet.com) ### Does Jane Street emphasize optimization over explanation? Jane Street’s published guidance puts the emphasis on collaboration and reasoning rather than on prior domain knowledge. The company’s main interviewing page says it focuses on “collaborative problem solving,” while the software-engineering guide says interviewers are trying to learn “how you work.” The mock-interview page does not say candidates are scored on micro-optimizations. (janestreet.com) Instead, the company’s own labels and advice center on communication, code quality and practice under interview conditions. Any broader claim that the clip changed how top firms interview would go beyond what Jane Street itself says; the company’s materials present the video as an example of its existing process. (janestreet.com) ### Where can readers check the source material? Jane Street’s mock interview remains available on the company website, alongside its broader interviewing and software-engineering preparation pages. Those pages identify the participants as Grace and Nolen and describe the exercise as a representative software-engineering interview using a retired question. (janestreet.com)