Problem Bank

Every problem, one index

The full shelf, arranged the way a serious practice index should be: filter it, sort it, and work it in any order. Difficulty is shown as Easy, Medium, and Hard. The site’s own tiers map onto those names directly, and the mapping is printed rather than hidden: Starter is Easy, Standard is Medium, Advanced is Hard.

A problem is Solved when a scored Case Room run averages at least 3.5 of 5 across the rubric lines, or when a graded data problem is submitted correctly and recorded. That is the same completion the leaderboard counts. Attempted means a scored run exists below that line, and Untouched means nothing has been recorded yet. Sandbox practice is never recorded, so it never changes a state here.

Create a free account and your state on every problem is tracked here. The leaderboard is opt-in and off by default.

Across all members, the shelf is being worked in the open: every row shows the community solve rate, the share of members with a recorded attempt who solved the problem, counted live from the same recorded work the leaderboard recognizes. A problem nobody has attempted yet shows no rate, because there is no honest rate to show.

Problem sets

Ordered paths through the bank for members who want a sequence instead of a shelf. A set is a suggestion, never a lock: every problem in it can be opened on its own.

The bank