Finding a problem

The filters on the problem list, what the acceptance rate means, why a topic page is worth browsing, and how to get an unsolved one at random.

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/problems is the whole catalogue. It is a public page - you can read and filter it signed out, though two of the filters only mean something once we know who you are.

Reading a row#

Each row carries five things, in this order: your status, the number and title, its topics, its acceptance rate, and its difficulty. On a narrow screen topics and acceptance drop away; status, title and difficulty always stay, because difficulty is the column the list is actually read down.

The status column is a tick for solved and a dot for attempted-but-not-solved. Signed out it is blank - that is "we do not know", not "you have not solved it".

The acceptance rate#

The share of submissions on that problem that were accepted. It sits next to the difficulty label on purpose: a problem marked Hard that most people solve first try is a label worth doubting, and showing both lets you doubt it.

The filters#

  1. Search matches the title. It filters what is on screen rather than asking the server again.

  2. Difficulty - Any, Easy, Medium or Hard.

  3. Progress - All problems, Not solved, Solved, or Attempted. This one only appears when you are signed in, because none of those questions has an answer otherwise.

  4. Random opens a random problem from the list you are currently looking at. Filter to unsolved mediums first and you get a random unsolved medium, which is almost always what people mean.

Changing any filter takes you back to the first page. Without that, filtering to Hard from page 4 of Medium lands you on an empty page 4 and reads as "no problems match" for a filter that matches plenty.

Paging#

The count above the list reads Showing 10 of 137 - the second number is the whole filtered result, not the page. Your own account-wide solved count lives in the sidebar card instead, where it always describes the entire catalogue rather than whatever is on screen.

Browsing by topic#

Every problem carries one to five topics, the first being its primary one. The full taxonomy sits at the foot of the list, grouped into four families - Data Structures, Algorithms, Techniques and Maths

  • and each is a real page at /problems/topic/<topic>.

Topic pages are worth using rather than being a filter in disguise: they are server-rendered, they link to each other, and they are the pages that turn up in a search engine. If you want to drill one idea - every sliding-window problem, in order - that is the page to bookmark.

The sidebar#

To the right of the list (below it on a phone) sit three cards:

  • Your practice - solved counts by difficulty, your streak, and a twelve-week activity strip. It is an invitation to sign in when you are not.
  • Browse by topic - the ten largest topics.
  • Not sure where to start? - a link to tracks, which is the honest answer to a long list of problems and no opinion about which to do next.

The full version of that first card, including every submission you have made, is your practice dashboard.

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