SpacedLeet is an extension that helps you organize your LeetCode problems' reviews using spaced repetition, a scientifically-proven method to efficiently retain information. Using spaced repetition, correctly answered LeetCode questions are later and less frequently for review, while incorrectly answered LeetCode questions are shown earlier and more often. According to Wikipedia, "Spaced repetition is an evidence-based learning technique that is usually performed with flashcards. Newly introduced and more difficult flashcards are shown more frequently while older and less difficult flashcards are shown less frequently in order to exploit the psychological spacing effect. The use of spaced repetition has been shown to increase rate of learning."