Video walkthroughs of Data Structures and Algorithms (DSA) questions typically found in competitive programming contests.
Are there in the same folder that might provide context? 640_147.mp4
Where did you (e.g., a specific website or course)? Video walkthroughs of Data Structures and Algorithms (DSA)
The identifier appears to be a internal tag used by the technical recruiting platform Nowcoder (牛客网) to categorize specific coding problems or company-specific recruitment content. In this context, it likely refers to a practice test or interview preparation module for a tech company like Kuaishou (快手). 640_147.mp4
If you downloaded this from a platform like Nowcoder or Bilibili, look for a corresponding "Problem ID" or "Lesson Title" on that site to find the written context.