← Jump Trading Interview Insights
My first instinct was to just collect filenames and filter, but I kept second-guessing myself on what counts as non-read.
Use a hash map to aggregate permissions per file, tracking whether any write or non-read permission appears. After processing all queries, collect files whose permissions are exclusively read. This yields O(n) time and O(m) space, where n is the number of queries and m is the number of unique files.
Pro tip: Clarify the permission model upfront—whether permissions are hierarchical (e.g., read < write < execute) or independent flags—as this affects the definition of 'non-read'. Also discuss edge cases like files with no queries or multiple owners.
Ask about the permission model, possible permission values, and whether a file can have multiple owners. Confirm that 'read-only' means no write or other non-read permissions across all queries.
Use a hash map to map each filename to a set of permissions or a boolean flag indicating if any non-read permission exists. Alternatively, use a set to track files that are not read-only.
Iterate through each query. For each file, if the permission is not 'read', mark the file as not read-only in the map. If it's 'read', ensure the file is recorded as read-only unless already marked otherwise.
After processing all queries, iterate through the map and collect all filenames that are still marked as read-only. Return this list.
Discuss time and space complexity (O(n) time, O(m) space). Mention edge cases: files with no queries, duplicate queries, and permissions like 'execute' or 'delete'.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.