Statement

Luca has been hired as an intern at Twitter to improve tools for understanding virality on social media. The company is known for having popularized the now widespread hashtags, constituted by the hash symbol # followed by a keyword, used to tag contents (especially tweets, in the case of Twitter). Each second, internal Twitter functions report the most used hashtag worldwide in that second (the most used hashtags signal the so-called trending topics). However, this level of granularity can be difficult to comprehend: for this reason, Luca wants to create a tool that aggregates data and reports the most popular hashtag for each given period of time lasting T seconds. For example, when T = 60 seconds, the tool should output the most used hashtag in the first minute (seconds 0 to 59, inclusive), then the most used one in the minute that lasts from second 1 to second 60 (inclusive), and so on...